The effects of ethylene-dibromide (106934) (EDB) on fertility and semen quality were studied in rabbits. Male New-Zealand-rabbits were injected subcutaneously with 15, 30, or 45mg/kg EDB daily for 5 days. They were observed for clinical signs of toxicity. Weekly sperm samples were collected starting 6 weeks before exposure and continuing for 12 weeks post exposure. The effects on sperm concentration, number, morphology, viability, velocity, linearity, beat cross frequency, amplitude of lateral head displacement (ALH), circularity and semen pH, osmolality, volume, acid-phosphatase activity, and fructose, citric-acid, carnitine, and protein concentration were determined. The effects on fertility were assessed by artificially inseminating three females per male with 1 million motile sperm before and 4 and 12 weeks after exposure and recording the number of impregnated females, litter size, and fetal body weight and examining the fetuses for malformations. The males were killed at the end of the study and necropsied. Hunched posture, lethargy, roughened coats, and hypothermia were seen in rabbits given 45mg/kg EDB. Three of ten rabbits in this group died. EDB at 45mg/kg caused significant decreases in sperm velocity, percentage motility, and ALH. Semen pH and ejaculate volume were significantly decreased in a dose related manner. Semen acid- phosphatase activity was increased in the 45mg/kg group. EDB did not significantly affect male fertility or cause any fetal malformations. Six of 10 rabbits in the 45mg/kg group had hepatocyte necrosis and bile duct hyperplasia. Two rabbits in this group showed inhibited spermiation in the testes. The authors conclude that EDB at doses close to the median lethal dose, 55mg/kg, cause changes in semen quality in rabbits similar to those seen previously in humans. This and other studies suggest that the rabbit may be a suitable model for studying male reproductive toxicity in humans.