Background: In recent years, significant advances have been made in our knowledge of the role of testosterone in male fertility and sexual function. In addition, new microsurgical techniques have improved outcomes in testicular biopsy for sperm retrieval, varicocoele treatment and vasectomy reversal. Objective: This article provides an update on the assessment and treatment of male infertility, and the role of testosterone replacement therapy and erectile dysfunction. Discussion: The evaluation of male infertility requires comprehensive history taking and a focused examination. Investigations that help form the basis for important treatment decisions include semen analysis and hormone testing. Further specialist assessment may be required to determine the need for genetic testing. There is increased evidence for the role of microsurgery in sperm retrieval, varicocelectomy and vasectomy reversal in men seeking paternity. Testosterone plays a role in both spermatogenesis and sexual functioning in a man. While testosterone replacement therapy can restore erections in androgen deficient men and treat other conditions related to hypogonadism, it can also result in male infertility.