We describe a rare case of apocrine adenoma of the breast in a 45-year-old man. The patient presented with a tender lump in his left breast that had been present for 6 months. A mammogram identified a 3-mm nodular density in the breast, which was described as a hypoechoic nodule on ultrasound. Microscopic examination of tissue from an excisional biopsy revealed a 3-mm group of benign glands with abundant granular, eosinophilic cytoplasm and apical luminal blebbing, consistent with an apocrine adenoma. After reviewing other reported apocrine adenomas in the literature, we determined that our case was the smallest detected apocrine adenoma to be reported to date.