The influences of dietary fumonisin B(1) (FB(1)), a metabolite of Fusarium verticillioides, on the onset of puberty, semen quality, fertility rates and testicular morphology in male rabbits (bucks) were studied. Forty male rabbits were randomly assigned and fed four diets containing 0.13, 5.0, 7.5 and 10.0 mg FB(1)/kg, constituting diets 1 (control), 2, 3 and 4 respectively, for a period of 175 days in a completely randomized design. During the last week of the feeding trial, two untreated female rabbits were mated to each of the four treated bucks per treatment to assess the fertility rate of the treated bucks. Onset of puberty in animals fed diets 3 and 4 was significantly (P<0.05) delayed by some 9-12 days. The weight at puberty, sperm concentration and total sperm/ejaculate were not significantly influenced by the dietary FB(1). Sperm mass activities, motility and live spermatozoa of the rabbits' semen significantly (P<0.05) declined with an increase in the dietary FB(1). The highest sperm cell abnormalities were recorded in the animals fed 10.0 mg/kg FB(1), while the least was observed in the control animals. The conception rate, litter size and embryo survival rate were statistically the same among the dietary treatments. Embryo mortality was significantly (P<0.05) higher in rabbits fed diets 3 and 4 than in others. Testicular elements were significantly (P<0.05) impaired by the toxin in rabbits fed 7.5 and 10.0 mg FB(1)/kg. This suggests that LOAEL of 7.50 mg/kg FB(1) delayed puberty, impaired semen quality and spermatogenesis and induced embryo mortality without a statistically adverse effect on the fertility rates of male rabbits.