The effect of pregnancy on the activity of rheumatoid arthritis (RA) was evaluated in 31 patients who had given birth to 49 infants after the onset of their disease. Pregnancy-associated remission of RA was experienced by 75% of the patients. On the other hand, disease exacerbation after delivery occurred in 62% of them. RA had no harmful effect on pregnancy or on the fetus. Hormonal changes during the menstrual cycle or during the use of hormonal contraceptives did not seem to influence the symptoms of RA. Factors possibly involved in remission of RA during pregnancy are discussed.