Testosterone replacement therapy (TRT) is a crucial intervention for men diagnosed with hypogonadism, a condition characterized by inadequate testosterone production. As primary care NPs play an essential role in managing patients with hypogonadism, they must comprehensively understand TRT. This article serves as a primer for primary care NPs, based on current guidelines, to provide evidence-based care for men with hypogonadism. It offers an overview of the etiology, clinical presentation, diagnostic criteria, and treatment options for hypogonadism, focusing on using TRT appropriately in primary care settings.