PIP: Serum LH (luteinizing hormone), FSH (follicle-stimulating hormone), and progesterone concentrations and urinary pregnanediol excretion were evaluated in 10 women before, during, and after chlomadinone therapy. 5 received .5mg continuously for 51-60 days; 5 received .5mg continuously for at least 6 months. A typical midcycle surge of LH and FSH was not found on any of the 5 short-term subjects during the treatment cycles. 4 of the 5 women showed a typical, mutiple elevations of the baseline concentrations of LH without concomitant rises in FSH. Pregnanediol excretion levels were low on 3 out of 5 women. 1 woman had relatively normal luteal phase progesterone in the first treatment cycle, and 2 in the second. All parameters reverted to normal patterns after withdrawal of the drug. In the long-term group, most women showed an increase in gonadotropin concentration; increased concentrations of FSH were more marked in subjects in the long-term study and progesterone levels reached 16 ng/ml.