The relationship between socio-economic indicators, family size, history of tonsillectomy, infectious mononucleosis (IM) and other diseases and the risk of Hodgkin's disease (HD) was investigated in a hospital-based case-control study, conducted in the province of Pordenone, North-east Italy, between June, 1985 and March, 1990. One hundred and fifty-two HD cases (88 men and 64 women) and 613 controls (357 men and 256 women) were interviewed. Patients with 14 or more years of education had a 2-fold increased HD risk (95% confidence interval, CI: 1.0-3.9); such risk tended to be higher in patients with nodular sclerosis (NS) HD (odds ratio, OR: 4.4, 95% CI 1.8-11.0). Sibship size, birth order and tonsillectomy were not associated with HD risk. Cases and controls did not differ in the frequency or age at occurrence of common childhood infections. A history of IM, however, was found to be an important predictor of HD risk, in particular among NS HD (OR = 13.1, 95% CI 1.0-176.7). Past episodes of herpes zoster and of skin and genital warts were also associated with significantly increased HD risks. These data lend further support to the role of the IM agent (i.e., the Epstein-Barr virus) and, perhaps, of other viral infections and immunological alterations in the development of HD.