The treatment of male infertility has been revolutionised by advances in assisted reproductive technology. This concise and structured account, prepared by an authoritative international panel of experts, provides a consensus on the most effective and logical approach to the investigation and management of male infertility. It focuses attention on three key areas: history taking; clinical assessment of male fertility; and objective criteria for diagnostic categories. This approach complements the areas covered in the companion volume WHO Laboratory Manual for the Examination of Human Semen and Sperm-Cervical Mucus Interaction (CUP, fourth edition, 1999) and significantly expands upon the section on male infertility in the previous volume on the infertile couple, WHO Manual for the Standardized Investigation and Diagnosis of the Infertile Couple (CUP, 1993). This new, practical consensus will be an indispensable guide to good clinical management of all forms of male infertility.