Keith Wendorff wrote an answer about Marmot Motion Insulated Pant - Men's on January 23, 2011
I have a pair of these. I'm 5'10" 190# 34"waist. ordered large and they fit loose, have to use the side cinches. I like my pants to fit snug around the waist so will try a Medium.. I have scree in mediun and they fit perfect.