Objectives: This paper examines the evidence supporting testosterone replacement in aging males. Confounding factors contributing to low testosterone levels and challenges to diagnosis of the andropause will also be considered. Methods: A thorough review using an integrative approach citing published literature and the ongoing work of the authors. A search was performed using National Library of Medicine PubMed. Electronic and print journals available at the Texas Medical Center library were also considered. Results: Information based on collective trials in older men has added to evidence for benefits and side effects of testosterone replacement inferred from studies in younger hypogonadal patients and animal models. In general, most investigators agree with short-term safety but long-term safety is unknown. Testosterone therapy in aging males improves body composition, certain domains of brain function and may also decrease cardiovascular risk in biological models. Measurable clinical effects are less apparent. Potential risks include erythrocytosis, edema, gynecomastia, and prostate stimulation. The possibility of increased risk of clinically significant prostate cancer and cardiovascular disease has been considered. Conclusion: The search continues for an ideal replacement androgen and larger long-term studies are needed. At this time, androgen replacement is on a case-by-case basis and prostate cancer screening should be completed prior to instituting therapy. Routine androgen replacement therapy for aging males will have significant economic implications, and is not currently recommended.