I am 5'11", 155 lbs, and wear a size 31x32 in pants. If these pants are for fashion only then go with a small, but if you actually plan on exercising in them then medium is the way to go. I originally ordered a small and loved the fit but then my sister told me to do a squat and I almost ripped out of them. The medium still gives you a slim look, but has a little extra room for comfort and mobility.