I'm 6 feet tall.  I wear a medium because of the location of the shoulder seams and length of the sleeves. If I buy a large, the shoulder seams are on the side of my arms and the sleeves reach my elbows. While some companies make a Long Tall size, I have never seen a Medium Tall size shirt. The tail on this shirt is very short. Unless you are 5' 7" or shorter, or want to show your plumbers crack every time you bend over, I don't recommend these shirts.