A case of synchronous adrenocortical carcinoma (ACC) and renal cell carcinoma (RCC) has not yet been described in the English medical literature, to our knowledge. We report a first such case of adrenocortical and renal cell carcinomas occurring simultaneously in a 53-year-old male. He presented with history of vague abdominal pain. Ultrasound followed by a computed tomography (CT) scan and a magnetic resonance imaging (MRI) examination revealed a 6.4 cm left adrenal mass and a 3.5 cm right renal mass. The patient had complaints of gastroparesis manifesting with constant nausea as well as intermittent abdominal bloating and abdominal pain. He also had history of profuse intermittent sweating. There was no history of palpitations or fluctuations in blood pressure. The patient's urinary vanillylmandelic acid (VMA) levels and serum cortisol levels were normal. His 24-hour urine metanephrine levels were slightly elevated. Left adrenalectomy and right partial nephrectomy were performed. In this case, it is important to determine whether these tumors represent metastases or two synchronous tumors, as this has implications on the patient's management and prognosis. Clinical and pathological clues that led to the diagnosis are discussed in detail.