Purpose: To support nurse practitioners in their encounters with aging male patients with signs and symptoms related to the decline of male sex hormones. Data sources: An electronic search was conducted on studies from 2006 to 2013 from the following databases: PubMed, CINAHL, Scopus, and related health resources websites. The search terms used included male menopause, andropause, androgen deficiency, testosterone deficiency, late-onset hypogonadism, and testosterone replacement therapy. Relevant studies in English were selected for an integrative review. Conclusions: Androgen deficiency syndrome has been overlooked in clinical settings. However, there has been an increase in health needs related to low testosterone levels. A diagnosis should be made carefully, considering other possible causes of the problems as well as the decision to initiate testosterone treatment (TT) and monitoring. In this article, the current awareness of androgen deficiency syndrome, pathophysiology of aging men's sex organ, clinical presentation, differential diagnoses, diagnostic strategy, clinical management, monitoring, and referral plans are discussed. Implications for practice: The rapidly growing aged population in our society makes androgen deficiency syndrome a growing issue that needs to be understood, adequately diagnosed, and carefully managed by nurse practitioners.