The article presents a case study of a 23-year-old horse which was brought to the Oklahoma State University Boren Veterinary Medical Teaching Hospital for euthanasia due to an enlarged prepuce and mass on its glans penis. The histologic, clinical, and gross examination of the horse revealed squamous cell carcinoma of the penis with metastases to the heart, lungs, and lymph nodes. It adds that squamous cell carcinoma is the most common neoplasm of the prepuce and penis in horses.