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Men's Underwear

(197 products)

Products (197)

Sort: Best Match

REI Co-opMerino 185 Base Layer Bottoms - Men's
$79.95
138 reviews with an average rating of 4.3 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
Top Rated
REI Co-opMerino 185 Long-Sleeve Base Layer Top - Men's
$79.95
199 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
tasc PerformanceElevation Merino Base Layer Bottoms - Men's
$34.73 - $54.73
Save 30% - 56%
compared to $79.00
Save up to 30% extra on your REI Outlet purchase, thru 12/16.
36 reviews with an average rating of 3.8 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
REI OUTLET
Top Rated
SmartwoolClassic Thermal Merino Base Layer Bottoms - Men's
$115.00
628 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
REI Co-opMidweight Base Layer Bottoms - Men's
$54.95
88 reviews with an average rating of 4.4 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big, Tall
Top Rated
SmartwoolClassic Thermal Merino Crew Base Layer Top - Men's
$115.00
1493 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
Top Rated
REI Co-opMidweight Long-Sleeve Base Layer Top - Men's
$54.95
178 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
tasc PerformanceElevation Merino T-Shirt - Men's
$34.73 - $54.73
Save 30% - 56%
compared to $79.00
Save up to 30% extra on your REI Outlet purchase, thru 12/16.
45 reviews with an average rating of 4.3 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
REI OUTLET
New arrival
TerramarPerformance Briefs - Men's - Package of 3
$19.73
Save 34%
compared to $30.00
Save up to 30% extra on your REI Outlet purchase, thru 12/16.
1 reviews with an average rating of 5.0 out of 5 stars
Size Type:
Regular, Big
REI OUTLET
Top Rated
REI Co-opLightweight Long-Sleeve Crew Base Layer Top - Men's
$27.93 - $39.95
25 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big, Tall
Top Rated
SmartwoolClassic All-Season Merino Long-Sleeve Base Layer Top - Men's
$66.93 - $90.00
77 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
REI Co-opMerino Boxer Briefs - Men's
$39.95
111 reviews with an average rating of 4.2 out of 5 stars
Size Type:
Regular, Big
Top Rated
REI Co-opMerino 185 Long-Sleeve Half-Zip Base Layer Top - Men's
$89.95
114 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
Top Rated
SmartwoolClassic Thermal Merino Quarter-Zip Base Layer Top - Men's
$120.00
36 reviews with an average rating of 4.6 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
Top Rated
REI Co-opMidweight Base Layer Half-Zip Top - Men's
$59.95
161 reviews with an average rating of 4.6 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big, Tall
Top Rated
REI Co-opHeavyweight Merino Base Layer Bottoms - Men's
$99.95
10 reviews with an average rating of 4.6 out of 5 stars
Underwear Weight:
Heavyweight
Size Type:
Regular, Big, Tall
Top Rated
IcebreakerMerino 200 Oasis Long-Sleeve Crewe Thermal Top - Men's
$105.00
177 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
Top Rated
REI Co-opLightweight Base Layer Bottoms - Men's
$39.95
19 reviews with an average rating of 4.6 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big, Tall
Top Rated
IcebreakerMerino 200 Oasis Base Layer Leggings with Fly - Men's
$105.00
66 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
REI Co-opHeavyweight Merino Long-Sleeve Base Layer Crew Top - Men's
$99.95
31 reviews with an average rating of 4.4 out of 5 stars
Underwear Weight:
Heavyweight
Size Type:
Regular, Big, Tall
SaxxVolt Breathable Mesh Boxer Briefs - Men's
$26.73
Save 23%
compared to $35.00
Save up to 30% extra on your REI Outlet purchase, thru 12/16.
6 reviews with an average rating of 4.0 out of 5 stars
Size Type:
Regular, Big
REI OUTLET
Top Rated
PatagoniaCapilene Midweight Base Layer Bottoms - Men's
$89.00
58 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
SaxxQuest Boxer Briefs - Men's
$24.73
Save 27%
compared to $34.00
Save up to 30% extra on your REI Outlet purchase, thru 12/16.
3 reviews with an average rating of 4.7 out of 5 stars
Size Type:
Regular, Big
REI OUTLET
Top Rated
IcebreakerMerino 200 Oasis Long-Sleeve Crewe Thermal Top - Men's
$78.73
Save 25%
compared to $105.00
Save up to 30% extra on your REI Outlet purchase, thru 12/16.
74 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Big, Regular
REI OUTLET
REI Co-opEveryday Boxers - Men's
$22.95
129 reviews with an average rating of 4.2 out of 5 stars
Size Type:
Regular, Big
SaxxVibe Xtra Soft Comfort Boxer Briefs - Men's
$24.73
Save 27%
compared to $34.00
Save up to 30% extra on your REI Outlet purchase, thru 12/16.
0 reviews
Size Type:
Regular, Big
REI OUTLET
Top Rated
PatagoniaCapilene Midweight Crew Base Layer Top - Men's
$89.00
87 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
SmartwoolIntraknit Thermal Merino Crew Base Layer Top - Men's
$92.73
Save 28%
compared to $130.00
Save up to 30% extra on your REI Outlet purchase, thru 12/16.
10 reviews with an average rating of 4.0 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
REI OUTLET
Top Rated
Arc'teryxRho Merino Wool Crew Neck Base Layer Top - Men's
$120.00
37 reviews with an average rating of 4.8 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
SmartwoolClassic All-Season Merino Base Layer Bottoms - Men's
$90.00
20 reviews with an average rating of 4.1 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big

1–30 of 197 products

Sort: Best Match

Related Expert Advice articles

What material is best?

Wool is moisture-wicking and odor-resistant, while synthetic fabrics are more durable and less expensive.

Match the temp to the trek

Lightweight layers are best for moderate to cool temperatures. Midweight layers are best for cold temperatures. Heavyweight layers are best for below-freezing temperatures.

Find your fit

To be able to wick sweat efficiently, your next-to-skin layer needs to actually be next to your skin. A comfortably snug fit everywhere is your goal.

Read full article: How to Choose Base Layers

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