Luteal phase deficiency, diagnosed by endometrial biopsy, was found in 1 out of 25 control fertile women and in 46 out of 355 infertile patients, a difference that was not significant. It was also found in 19 [corrected] out of 60 patients with early recurrent abortion which was significantly higher than in controls and in infertile patients. Pregnancy outcome was evaluated in treated and untreated groups of patients diagnosed as having luteal phase deficiency. Our data suggest that treatment improved the results of pregnancy in patients with recurrent abortion, but not in infertile patients.