1. Urine free dopamine was estimated at predetermined points of the menstrual cycle in normal volunteer subjects and in women taking a combined oral contraceptive.
2. There was no alteration in 24 h urine dopamine during the normal menstrual cycle but, in contrast, combined oral contraceptives produced a fall which recovered premenstrually.
3. In 19 primigravid subjects 24 h urine free dopamine was estimated at monthly intervals throughout pregnancy and at the time of the postnatal examination.
4. Urine dopamine was elevated throughout pregnancy when compared with postnatal values. Women receiving an oral progestogen contraceptive at the time of the postnatal examination showed a further fall in urine dopamine.