Well, thats hard to say because some websites say different things. Some say 3-6 months, some say a year, I guess it all depends on how often you wear them, and how good you take care of them. I only wear mine like once a month if that. I got them about a year ago and just now wore them outside my house. lol I put them in to take photos, till this last weekend, I actaully wore them out to a bar. They are made of Polymacon and so far almost every lens I see that is made of that, and that are in vials last about a year if you wear them daily. But I would ask your eye doctor just to be sure. Here is the link to the website I ordered them from. You do need a perscription for any colored lens that you can email or fax them. As long as the "size" of the lens is the same, they will ship them to you. http://www.cosmetic-lens.com/ They have other brands to that are really cool, Like Europa (more for lighter eyes) and Pacifica (non-perscription-also for lighter eyes) and a few others. Check it out!