To evaluate the role of pregnancy in the pathogenesis and clinical course of Hodgkin's disease (HD), we studied a series of 192 female patients aged 17-50 years at the time of diagnosis, and 496 healthy controls matched by residence and year of birth. Cases showed a marginally significant excess for the father having a high level of education, and more families were classified as white-collar workers than as industrial workers. No significant differences between cases and controls were found in other parameters describing the family and living conditions in childhood. Before the age when cases were diagnosed, 35.4% of cases and 34.7% of their controls were nulliparous. Among the cases, the mean age at first delivery was 22.4 years, with a total of 201 children (average: 1.05 per case) born before diagnosis; for the controls, the corresponding figures were 22.2 years and 573 children (average: 1.15). Within the first 6 months after the last delivery, HD was diagnosed in 12 of 124 parous cases (9.7%); for controls, the corresponding number is 18 out of 324 (5.6%). A marginally significant negative trend (P = 0.07) in odds ratios is seen with increasing duration of this interval. We conclude that our study could not confirm previous reports of a protective effect of pregnancy for the risk of HD. On the other hand, marked physiological changes in the period of puerperium may accelerate the expression of HD.