This case-control study explored the role of environmental toxins in male infertility in patients attending an assisted reproduction clinic in southeastern Spain. Exposures were compared by questionnaire for 30 infertile oligoasthenoteratozoospermic males (cases) and 31 normozoospermic controls residing in the area. Odds ratios and 95% confidence intervals (CI) were used to estimate differences in lifestyle and chemical occupational exposures. More than two-thirds of the cases (23/30), compared with less than one-third of controls (10/31), had been exposed occupationally to at least one toxin or pollutant (OR = 6.9; 95% CI: 2.2-21.4) and were also more exposed to them currently (OR = 5.2; 95% CI: 1.6-17.2). Exposure to glues, solvents or silicones (OR = 22.9; 95% CI: 2.8-190.9), metals (OR = 8.8; 95% CI: 1.4-54.2) and physical agents (OR = 7.3; 95% CI: 1.4-36.7) in the past, as well as current exposure to glues, solvents or silicones (OR = 10.4; 95% CI: 2.6-42.5) and physical agents (OR = 4.7; 95% CI: 1.1-19.2), were significantly higher in cases than in controls. Average duration of exposure was also significantly higher in cases (P < 0.001). This study suggests that male infertility in patients attending infertility clinics may often be the result of occupational exposure.