Copper is an essential trace element that is strongly bioaccumulated. In this study the effects of this environmental contaminant on various spermatozoa motility parameters in vitro was analyzed. Rabbit spermatozoa were cultured with copper (CuSO(4).5H(2)O) which was added to semen in 5% solution and subsequently diluted 1:1-10. Analysis was carried out using a Computer Assisted Semen Analyzer (CASA) system in 3 time periods (0, 60 and 120 minutes). At Time 0, the highest motility in control group was detected. Motility in groups with copper administration was significantly (P < 0.05) decreased to 8.25-19.37%. The decrease of progressive motility was even more significant - in control 73.37 +/- 7.01% and in experimental groups up to 0%. At Time 60, motility significantly (P < 0.05) decreased from 59.62 +/- 11.40% to 7.50 +/- 3.66%. Progressive motility decreased from 49.62 +/- 16.10% to 0% in the group with the highest copper concentration. After 120 minutes of incubation the motility was 57.75 +/- 5.82% in control group and in all experimental groups it significantly (P < 0.05) decreased to 8.75%. Detailed evaluation of spermatozoa distance (DCL - distance curved line; DAP - distance average path; DSL - distance straight line) and velocity (VCL - velocity curved line; VAP - velocity average path; VSL - velocity straight line) parameters detected significant (P < 0.05) decrease in all studied markers in groups with copper addition in comparison with control group at all time periods. Straightness, linearity, wobble, amplitude of lateral head displacement and beat cross-frequency of spermatozoa were altered weakly. Detected data clearly confirm negative effects of high copper concentrations in semen on spermatozoa motility parameters and subsequent reproductive alteration in male sexual functions.