We report a case of renal cell carcinoma in acquired cystic disease of the kidney (ACDK) presenting with a spontaneous renal rupture. A 41-year-old man on chronic hemodialysis for 16 years was referred to our hospital with sudden left back pain. On arrival, the patient was in a state of hemorrhagic shock but his general condition improved by conservative therapy. Computed tomography demonstrated a left renal rupture as well as bilateral ACDK. Although there was no definite evidence of a renal tumor, a left radical nephrectomy was performed one week later. The resected kidney contained a yellowish-brown tumor of 5.5 x 5.0 x 4.5 cm in size. Pathological examination revealed renal cell carcinoma, cystic type, clear cell subtype, pT2pN0M0. He has been free of recurrence for 3 months.