A case-referent study nested in a cohort monitored biologically for exposure to six organic solvents (styrene, toluene, xylene, tetrachloroethylene, trichloroethylene, and 1,1,1-trichloroethane) was conducted to investigate the effects of paternal exposure on pregnancy outcome. The pregnancies were identified from medical registers. The exposures of the men during the spermatogenesis preceding the pregnancies and of the women during the first trimester of the pregnancies were obtained with questionnaires, and the available biological monitoring measurements were used in the exposure assessment. Factors which significantly increased the odds ratio of spontaneous abortion were paternal exposure to organic solvents in general, high/frequent exposure to toluene or miscellaneous organic solvents (including thinners), and maternal heavy lifting. No significant association between paternal or maternal exposure and congenital malformations was found, but because of the few cases no firm conclusions can be drawn.