You are using a web browser we don't support. Please use the latest version of one of these browsers.

Mozilla Firefox

Google Chrome

Apple Safari

Microsoft IE

Back to top
Channel Blue
Channel Blue

This product is no longer available, but don't go just yet.


  • Jersey-knit merino wool provides superior softness and odor-resistant performance; wool is processed without the use of chlorine
  • Recycled polyester enhances moisture wicking performance and increases durability
  • Raglan sleeves eliminate shoulder seams for increased range of motion and comfort
  • Hidden thumbholes under cuffs keep sleeves in place when arms are in motion
  • Underarm panels with offset side seams minimize abrasion and maximize motion
  • Slim fit
  • Machine wash the Patagonia Merino 3 Midweight Zip-Neck on cold; tumble dry on low


View all Patagonia Men's Long Underwear Tops

REI membership


Best Use Multisport
Shirt Style Zip-front
Fabric 80% merino wool/20% recycled polyester
Moisture Wicking Yes
Underwear Weight Midweight
Sleeve Length Long Sleeve
Gender Men's

The REI Difference

100% satisfaction guaranteed

We stand behind everything we sell. If you are not satisfied with your REI purchase, you can return it for a replacement or refund within one year of purchase.

REI's guarantee doesn't cover ordinary wear and tear or damage caused by improper use or accidents.

If your item has a manufacturing defect in its materials or workmanship, you can return it at any time. See our limited warranty.

Gear & advice you can trust

At REI, we live and breathe the outdoors, and we're passionate about sharing our expertise with people of all skill levels. Whether you're new to the outdoors or a seasoned explorer, we'll take the time to understand your needs and help you find the right gear for you.

10% annual member refund

Anyone can shop at REI, but for a one-time $20 fee you can become an REI member and enjoy a lifetime of benefits. These include an annual member refund, typically 10% back on eligible purchases.*



*10% is typical but not guaranteed. Your refund is based on eligible purchases, which exclude REI gift cards, services, fees, REI Adventures trips, REI Garage, and discounted items. Learn more