AbstractMethylmalonic acidemia (MMA) is an inborn error of metabolism caused by either deficiency of the enzyme methylmalonyl‐CoA mutase or a defect in adenosyl‐cobalamin synthesis. Chronic kidney disease is its common complication and, in combination with persistent acidosis, leads to hyperuricemia. Symptomatic hyperuricemia or gout, however, has not been reported in MMA. We herein report two pediatric cases of MMA caused by MMAB mutations (cblB defect) with renal tubular acidosis, chronic kidney disease, hyperuricemia, and gout. The clinical findings of gout in these cases included recurrent first metatarsophalangeal arthritis and/or tophi. The patients responded to treatment with colchicine and allopurinol.