PIP: A pharmacological evaluation of centchroman (3,4-trans-2,2,dimethyl-3-phenyl-4-p-(beta-pyrrolidino ethoxy)-phenyl-7-methoxychroman), a new postcoital contraceptive, in normal healthy human volunteers was performed to determine the maximum tolerated dose and to discover any abnormal toxic effects in humans. The study was carried out for both men and women as a double-blind noncrossover trial in 2 parts: 1) a single dose study (40 volunteers) and 2) a multiple dose study (28 females) for 30 days. Centchroman was well tolerated without significant side effects in single doses up to 320 mg, severalfold higher than the anticipated therapeutic dose. In the multiple dose schedule, the compound was found safe at doses of 60-120 mg/day. however, similar effects were observed in subjects receiving placebo and are not unexpected in a normal population over a 1-month period. Centchroman is presently undergoing clinical trials for postcoital contraceptive efficacy in humans.