Reading most of the reviews on here, I followed the advice of others and ordered the "Larger" size. I'm a musclar 5'7/155lbs and the shirt does fit pretty good. However, the neckline is a lot larger than I anticipated.

The arms on the shirt are a big snug but the material stretches so it's not too bad. Overall I would say that this is a nice shirt, just be warned that the neckline is larger than the picture posted.