A population-based case-control study was conducted on 593 cancer cases in children from 0 to 14 years of age diagnosed in Moscow from 1986 to 1988. The study included 1181 healthy controls matched by age, gender and residence. Parental exposures prior to conception, including exposures to petroleum products, organic solvents, unspecified chemicals, soldering aerosols, ionizing radiation, electromagnetic fields (EMF), visual display units (VDU) and high temperature in the work environment, were significantly more frequent among the cases than among the controls (p < 0.05). Leukemia risk was associated with paternal exposure to ionizing radiation [odds ratio (OR) 6.7; 95% confidence interval (CI) 2.8-15.8], EMF (OR 4.6; 95% CI 1.8-11.9), VDU (OR 2.4; 95% CI 1.0-5.8) and unspecified chemicals (OR 2.0; 95% CI 1.02-4.1). Leukemia risk was also higher when mothers were exposed to solvents (OR 3.1; 95% CI 1.5-6.3), unspecified chemicals (OR 2.0; 95% CI 1.0-4.3), ionizing radiation (OR 10.3; 95% CI 1.3-83.4) and EMF (OR 5.2; 95% CI 1.6-16.8). Increased risk of non-Hodgkin's lymphoma was shown to be related to maternal exposure to oil products (OR 3.3; 95% CI 1.01-10.7) and unspecified chemicals (OR 3.3; 95% CI 1.01-10.7). Exposure to VDU was found to be associated with increased risk of neuroblastoma (6/1; OR 13.8; 95% CI 1.9-100.0).