This shirt is pretty sick. I am athletic built and this shirt was a little too big for me in Medium size. The sleeves went to my elbows and looked a bit too saggy, especially length wise. I got the small and it fit just fine. After washing it does get a bit smaller, but it gives it the look of a slim fit shirt if you like that style. Overall, if you are around 5'8" and athletic/skinny built, the small should suffice if you want the slim fit look. Otherwise, the medium is great especially if you wash it correctly.