Semen collected from 10 New Zealand white bucks by artificial vagina was diluted with citrate-based diluent to a concentration of 50 × 10 6 spermatozoa ml −1. Aliquots were supplemented with PGF 2α at levels of 0, 300, 600 and (1200) μg ml −1 and incubated at 37 °C for 4 h. The percentages of damaged acrosomes increased significantly ( P < 0.005) with increasing PGF 2α levels and incubation time. Activities of glutamic-oxalacetic transaminase and glutamic-pyruvic transaminase were stimulated significantly ( P < 0.005) with the increase in the PGF 2α levels, whereas the incubation time showed no significant effect. The release of lactic dehydrogenase into the extracellular medium increased significantly with PGF 2α levels and incubation time. These results suggest that supplementation of diluted rabbit sperm with PGF 2α (300 μg ml −1 or more) increased sperm membrane damage and permeability.