Eighteen women with polymyositis/dermatomyositis (PM/DM) were studied to determine the possible influences of pregnancy on the disease and the influence of the disease on pregnancy. Before the onset of PM/DM there were 77 pregnancies: 7 (9%) ended in abortion, 2 (2.5%) in perinatal deaths, with a total fetal loss of 11.5%. There were 3 (3.8%) premature newborns that survived. These figures are equivalent to those of the general population. There were 10 pregnancies in 7 patients coinciding with PM/DM, 1 of them with twins; 3 (30%) ended in abortion, 3 (25%) in perinatal deaths, with a total fetal loss of 55%, and 5 (50%) pregnancies ended prematurely. Four of the 7 women had onset of PM/DM during pregnancy, and 3 others with previously inactive disease had an exacerbation during pregnancy. There were no maternal deaths, nor was there any correlation between activity of PM/DM and fetal loss. These results together with those previously reported suggest that pregnancy in PM/DM should be considered high-risk for both the mother and the baby.