Maplewood Rusty was a two year old male Clydesdale horse that presented with a chief complaint of stallion-like behavior following removal of the right testicle, which was the only one that had descended. Physical exam revealed a healthy horse, and a left testicle that could not be palpated. Laparoscopy was performed to remove the abdominally cryptorchid testicle, and a large cystic structure associated with the testicle was found. 3.5 liters of clear yellow fluid were drained off the cyst to allow removal of the testicle. The testicle was submitted for histopathology, which revealed a mix of testicular, neuronal, salivary, and thyroid tissues. Histologic diagnosis was testicular teratoma. Recovery from surgery was normal, and long term prognosis is excellent.