Epidermal cysts are commonly encountered, slow-growing superficial cysts in the hair-bearing areas of the body, and are usually discovered in the second and fourth decades of life. These cysts tend to be superficial, meaning that they can be easily found by ultrasound and digital palpation at a moderate degree of growth. However, we found a huge testicular cyst that went undetected until old age. In this report, we describe the interesting case of a patient in whom the right testis was totally replaced with an epidermal cyst. The cyst was found by ultrasonography and further evaluated with magnetic resonance imaging. We performed orchiectomy under the impression of an epidermal cyst. The pathologic report confirmed this clinical impression. Over 24 months of follow-up, we did not find any recurrence of a growing mass on the testis.