After 15 years of clinical experiences with Clomiphen treatment it seemed desirable to investigate the efficiency of this kind of therapy under routine conditions in a crowded out-patient clinic. 314 patients treated from 1972--1974 have been included in this study. From 242 sterility patients 730 cycles could be followed. 80.2% were ovulatory, but 23.5% had an insufficient luteal phase and 11.9% of these cycles ended with an anovulatory bleeding. The overall pregnancy rate was 30%. Side-effects were recorded in 4.5% but all of them were harmless, no overstimulation occurred. After discontinuation of Clomiphen therapy 8% of all patients had spontaneous cycles. In 36 patients with eugonadotropic secondary amenorrhea with a total of 115 treatment cycles ovulation was recorded in 58%. Pregnancy rate was 25%, the intensity of treatment 3.1. In 54 patients with anovulatory cycles 156 cycles (72,3%) became ovulatory, pregnancy rate was 24%, the intensity of treatment 3.5. In another group of 19 patients with oligomenorrhea ovulation occurred in 39 of 42 cycles, 4 patients became pregnant. In 108 patients with luteal phase defects in 338 cycles ovulation was found in 90.2%, with 26.6% of these cycles being still insufficient. The pregnancy rate was 18.5%, the intensity of treatment 3.7. 9.8% of these 338 cycles became anovulatory during clomiphen treatment. In 27 patients with "insufficient cycles" in 104 treatment cycles nearly all of them were ovulatory but 20% of them were found to have an insufficient corpus luteum phase. The pregnancy rate was 30%. The highest pregnancy rate was found during the first 3 treatment cycles (26%). It is consequently our policy to treat patients 4 to 6 times with clomiphen and when no pregnancy can be achieved, these patients should be treated with HMG/HCG. 65 of 73 pregnancies were followed, 52 patients were delivered with healthy babies, 12 patients aborted. Of the total number of 54 babies born, 47 were single, 6 were twins, 2 babies were stillborn. The sex ratio (male to female) was 2.2. No malformations were found. In our group of patients other factors besides ovarian dysfunction contributed to the relatively low pregnancy rate. Thus, in 116 out of 244 patients one tube was occluded, while adhesions were found in 99 treated with clomiphen as a diagnostic step to convince the patient, that stimulation of ovarian function will be possible whenever the patient desires to become pregnant. The ovulation rate in this group was 38% in addition 37% responded with anovulatory bleeding, thus, 74% of all patients experienced a positive reaction from their point of view. After discontinuation of clomiphen administration 18% of these patients continued to bleed with (7.5%) or without (10.6%) clinical signs of ovulation. A further observation is the obvious fact that clomiphen therapy free intervals can be interposed without risk of a lower success rate, compared to patients receiving continuous cycle to cycle treatment.