11-Ketotestosterone (11-KT) is an oxidized form of testosterone that contains a keto group at the C11 position.

It is related to adrenosterone, an androgen found in trace quantities in humans.

In fish, 11-ketotestosterone functions as the endogenous androgenic sex hormone.

[1][2] In midshipman fish, 11-ketotestosterone is not present in females or Type II Males — Type II Males reach sexual maturation later, are less territorial, and have higher testosterone than Type I Males.

[3] 11-Ketoandrostenedione has notably been sold online as an androgen prohormone, usually under the name 11-oxoandrostenedione (11-OXO).