Approximately 30% of cases of couple infertility are due to a male factor. Several conditions can interfere with spermatogenesis and reduce sperm quality and production. Treatable conditions, such as hypogonadism, varicocele, infections and obstructions, should be diagnosed and corrected, but many aspects of male factor infertility remain unclear. Various agents have been used in the attempt to increase the fertility potential of subjects with idiopathic oligoteratoasthenozoospermia. The rationale of medical treatment to improve sperm quality in these subjects has been questioned by the introduction of assisted reproductive technologies. However, there is now growing awareness of the importance of good quality spermatozoa for embryonic development and higher birth rates. Confounding factors in assessing the efficacy of male infertility treatments have erroneously inflated the superiority of assisted reproductive technologies over conventional approaches. A systematic review is given of relevant randomized controlled trials and effects on semen parameters. The analysis reveals that although results are heterogeneous, gonadotrophins, anti-oestrogens, carnitine and trace elements may be beneficial in improving sperm quality, although their effect on pregnancy rate remains controversial. The most common drug regimens are compared and an estimate of the results expected from these treatments provided.