A total of 220 cows and heifers were treated with 3 mg/kg ketoprofen immediately after calving and 24 hours later, and 227 were left untreated as controls. The treated animals tended to have a lower incidence of retained fetal membranes and were 1˙7 times less likely to develop the condition than the untreated animals. The treatment did not affect the incidence of milk fever, the endometritis score or the presence of a corpus luteum by 20 to 25 days after calving, and did not affect the cows' early lactation milk yield. There was no particular level of dystocia or periparturient conditions other than retained fetal membranes for which there might be a reproductive or productive advantage following the use of ketoprofen. The intervals from calving to first insemination or to pregnancy, the numbers of inseminations per pregnancy and the pregnancy rate to first insemination were also unaffected by ketoprofen treatment.