Cancer registrations among young individuals (under age 30 years) for a 30-year period (1960-1989) were used to investigate the risk of cancer in migrants to Israel, and in their offspring, relative to Israel-born individuals with Israel-born parents. Relative risks of testis and ovarian cancer (germ cell tumours and carcinomas), melanoma, and carcinomas of nasopharynx, colorectum, breast, cervix and thyroid were calculated according to father's birthplace, and odds ratios for birthplace of mother, or of both parents. The estimates were adjusted for the effects of age, sex and time period. For 3 cancers, i.e., testis cancer, nasopharyngeal carcinoma and melanoma, there were quite large differences in incidence, which persisted to some degree into the second generation, suggesting that inherited susceptibility may underlie some of the variation. For ovarian, colorectal, cervical and thyroid cancers, differences in risk between the migrant groups had largely disappeared in their offspring, suggesting that environmental exposures, which were modified by migration, are the major causative factors.