Prostaglandin E 9-ketoreductase, NAD+-dependent 15-hydroxyprostaglandin dehydrogenase (type I), and NADP+-dependent 15-hydroxyprostaglandin dehydrogenase (type II) have been partially purified from swine renal medulla and cortex. Eleven times more NAD+-dependent 15-hydroxyprostaglandin dehydrogenase activity was found in the cortex than in the medulla. On the other hand, about twice as much NADP+-dependent dehydrogenase activity was found in the medulla than in the cortex. The prostaglandin 9-ketoreductase activities were equally distributed in the swine kidney cortex and medulla.