Semen analysis may be useful in both clinical and research settings, for investigating male fertility status as well as monitoring spermatogenesis during and following male fertility regulation and other interventions. This manual provides updated, standardized, evidence-based procedures and recommendations for laboratory managers, scientists and technicians to follow in examining human semen in a clinical or research setting. Detailed protocols for routine, optional and research tests are elaborated. This new edition comprises three parts: semen analysis, sperm preparation and quality assurance. The text includes descriptions of how to construct a conventional semen profile and provides standardized protocols for performing several optional diagnostic procedures. Such techniques are essential in the evaluation of infertile couples and in assessing fertility in men whose sperm production is suppressed by potential anti-fertility compounds or by toxic agents: they are also of interest in forensic medicine and in connection with artificial insemination. The fifth edition includes new information on sperm preparation for clinical use or specialized assays and on cyropreservation, an expanded section on quality control in the semen analysis laboratory and evidence-based reference ranges and reference limits for various semen characteristics. The methods described are intended to improve the quality of semen analysis and the comparability of results from different laboratories. Previous editions of this volume have been recognized as providing global standards in the area of fertility investigation and treatment, and have been used extensively by research and clinical laboratories throughout the world.