We present a case of a 49-year Turkish woman who had synchronous renal leiomyoma and breast cancer. The patient was evaluated for a suspicious breast mass; and renal mass was detected incidentally by contrast-enhanced computed tomography (CT). Diagnostic tru-cut biopsy was performed for both masses. Breast mass biopsy was reported as invasive ductal carcinoma (IDC) while renal biopsy was described as benign mesenchymal tumour. According to the biopsy results, the renal mass was followed for six months. For breast cancer, segmental mastectomy and concomitant sentinel lymph node biopsy was performed. Histologically, the tumour was reported as IDC and low-grade cribriform ductal carcinoma in situ (less than 1%). Six months later, renal mass was excised by laparoscopic approach. Histopathological examination was consistent with renal leiomyoma. For both tumours, no recurrence within one year was found on follow-up.