One known environmental risk factor impacting on human reproduction is heavy metal pollution. Although some metals (e.g., Cu, Se and Zn) have protective effects on the male reproductive system in low doses, heavy metals can accumulate to toxic levels and result in poor semen quality and decreased sperm function. We investigated the effect of CuSO and CdCl (10, 50, 100 and 250 µg/ml or 500 µg/ml) on human sperm motility and vitality by using computer-aided sperm analysis (CASA) and two cytotoxicity assays (WST-1 and XTT). Several sperm motility parameters were significantly reduced after 5 hr of exposure to the highest concentrations of CuSO (250 µg/ml) and CdCl (500 µg/ml). The WST-1 assay also revealed significantly lower absorbance values for 50, 100 and 250 µg/ml CuSO and for 500 µg/ml CdCl ; however, no significant effect was seen with XTT. The calculated average IC value was 50.31±  4.34 µg/ml for CuSO and 392.32  ±76.79 µg/ml for CdCl . The effects of these metals were confirmed with MgCl , a positive control. This study provides threshold concentrations for the harmful effect of CuSO and CdCl on human spermatozoa and recommends the use of WST-1 as vitality assay in future in vitro studies.