A case-control study of 271 testicular cancer cases aged 18-42, including 60 seminomas and 206 other germinal cell tumours, and 259 controls was carried out to study the association between occupation and testicular cancer risk. Study subjects were identified at three medical centres, two of which treat military personnel. Controls were men diagnosed with a cancer other than of the genital tract. Associations were identified between professional employment (administrators, teachers and other professionals) and risk for testicular seminoma, OR = 2.8 (95% Cl: 1.4-5.4) and between employment in production work and risk for other germinal cell tumours, OR = 1.8 (95% Cl: 1.1-2.7). No specific occupations within these broad groups were responsible for observed increases. Self-reported exposure to microwave and other radio waves was associated with an excess risk for both seminomas and other germinal cell tumours. However, an assessment of radio wave exposure based on job title did not support this finding. Although testicular cancer has been increasing in recent decades among young males, occupational factors did not appear to account for a substantial proportion of testicular cancer occurrence in the population studied.