To study the diagnostic value of various serological tests in the detection of serum sperm antibodies a group of 50 patients with azoospermia was studied. Cases were divided by testicular biopsy into: 32 obstructive and 16 non obstructive cases. Tests applied included a microagglutination and a macroagglutination test as well as 2 complement dependent tests; a sperm cytotoxic and a sperm immobilization tests. Applied separately the macroagglutination was the most sensitive test but used together, more cases were detected. Because of this and the different value and significance of each test, it is advisable to use more than one test in the investigations of cases of male infertility.