While family physicians may readily entertain genetic diagnoses in their pediatric patients, they may fail to consider such diagnoses in their adult patients. We present the case of a man with recurrent leg ulcers who was recognized as hypogonadal and was ultimately given the diagnosis of Klinefelter's syndrome (XXY) at age 47. Although there is no primary treatment for XXY, significant associated conditions, including osteoporosis and testosterone deficiency, can be ameliorated. We review the clinical condition of XXY at various ages and summarize age-specific interventions. We discuss the importance of genetic diagnosis throughout the life span.