I never wear anything under my yoga pants, I don't care about the pantylines but I do love the free feeling I get from wearing just the pants. I buy my pants at Mesa Yoga Apparel and Studio which carry a very light weight and sheer material made up of a combination of fabrics they manufacture. It actually feels like your not wearing anything and there is no tension in the material expansion during positions. They carry form fitting and loose fit baggy crotch types. I love both. I have been told by many people during and after classes that were behind me that both types of pants become very see through during stretches and that I should wear underwear because they can see everything as if I wasn't wearing anything at all. I don't care and kind of enjoy the attention. I enjoy watching the guys jockeying for positions behind me before class starts and the owner has told me that the amount of men attending classes have increased since I've been coming there. I told them they should have a coed nude class.