Patients with acquired cystic kidney disease (ACKD) are at an increased risk of renal neoplasms. Frequent tumors are adenomas and renal cell carcinomas. However, renal oncocytomas may occur in patients with ACKD. Little is known about oncocytomas of the native kidney following renal transplantation. By means of B scan ultrasonography, a solid and echo-inhomogeneous renal mass was incidentically observed in the right native kidney of a 28-year-old female patient with ACKD 4 years following renal transplantation. A nephrectomy was performed. The histological examination revealed a renal oncocytoma. The increased prevalence of neoplasms in the case of ACKD and following renal transplantation requires careful monitoring of the patients concerned. In very rare cases a renal oncocytoma may develop in the native kidney after renal transplantation.