What causes dark spots on my back?

DARK SPOTS ON BACK. Do these spots itch? How long have you had them? How dark are they? If they are tan, it may be a condition known as tinea versicolor. I would need a picture and a little more of a history. Male or female? Age? Tinea versicolor is relatively easy to treat, although very often it can recur and last for years. It is also mildly contagious, but not serious.