Based on a comparative study in a group of healthy men and men suffering from oligospermia and azoospermia, the authors consider it useful to examine FSH, LH, PRL and testosterone serum levels for possible evidence of testicular hypofunction and for detection of stress situations associated with raised PRL levels. As to seminal plasma, the authors consider it useful and relevant to assess citric acid levels, total acid phosphatases and in particular fructose with alpha-glucosidase.