Semen samples taken from 21 rams with pronounced pathologic changes were studied in a complex way to establish the etiology contributing to the deterioration of the semen quality. The complement-fixation test was applied with blood serum and semen plasma along with the microscopic study of the semen for the excretion of Brucella ovis organisms and a clinical examination. The following results were obtained: 1. The semen plasma of 90.5 per cent of the rams was positive for Brucella ovis. A total of 80.9 per cent were CFT-positive, and the same per cent of the animals were positive for the excretion of Brucella ovis organisms with the semen. The three diagnostic methods give equally positive results in 84.2 per cent of the cases. 2. The clinical examination revealed gross lesions in the genital apparatus in 33.3 per cent of the investigated animals, which coincided with the results obtained through the above-mentioned three methods in 85.9 per cent of the cases. 3. The simultaneous application of the blood serum and semen CFT, the bacteriologic investigation of the semen, and the clinical examination makes it possible to establish the etiology responsible for the defective spermogram of the rams studied.