Ten buffalo bulls, five with low sexual desire (G1) having a mean reaction time (RT) of 155.0 s and five contemporary bulls with a normal sexual desire (G2) having a mean RT of 56.8 s, were used. Semen was collected and reaction time was measured weekly through an experimental period of 12 wk. At the end of the experiment, each of scrotal circumference and wall thickness was measured. Peripheral blood plasma testosterone concentration was determined. Thereafter, all bulls were slaughtered and morpho-histometrics of testis and scrotum and morphology of penis were investigated.                 Results indicated that bulls in G1 had (P<0.01) a longer RT by about 173% and lower semen quality than those in G2. Significant (P<0.001) negative correlation coefficients were found between RT and semen characteristics. Testicular weight (TW) and volume (TV) were higher  (P<0.01) in G2 than G1 (163.6 g and 180.3 cm³ vs. 109.9 g and 110.7 cm³). Scrotal weight did not differ significantly between the two groups, however, scrotal circumference (SC) and wall thickness (SWT) were significantly (P<0.01) lower in G1 than G2 by about 17.0 and 20.3%, respectively. Reaction time correlated (P<0.001) negatively with TW (-0.40), TV (-0.53), SC (-0.88) and SWT (-0.78). Weight, length and diameter of the penis were significantly lower in the bulls with low sexual desire (G1) than in G2 (345.0 g, 83.8 and 4.0 cm vs. 243.2 g, 72.6 and 3.4 cm). However, weight of retractor muscle and weight, length, width and thickness of ischiocavernous muscle did not differ significantly between the two groups.                 Level of peripheral plasma testosterone in bulls of G1 was significantly (P<0.05) lower by about 46.3% than G2, which was associated with a decreased (P<0.05) proportion of the testicular parenchyma in G1 than in G2 (11.0 vs. 20.2%). Thickness of scrotal epidermis and smooth muscle layer (Tunica dartos) was significantly (P<0.05) thinner in G1 than in G2, however, thickness of scrotal dermis did not significantly differed. The study indicated the presence of relationship between the sexual desire of buffalo bulls and the morpho-histometrics of the testes and the scrotum.