Topiramate is an antiepileptic medicine that has been used adjunctively in the treatment of refractory seizures in Japan since 2007. Topiramate has been shown to inhibit specific carbonic anhydrase activity in the kidney and may induce a distal type of renal tubular acidosis. Case 1 : A 22-year-old male was referred to our hospital after complaining of left flank pain. He developed a seizure disorder and had been using topiramate for 4 months. Drip infusion pyelography showed a left ureteral stone. Case 2 : A 7-year-old boy presented with gross hematuria. He developed West syndrome and had been using topiramate for 6 months. A computed tomographic scan showed a right kidney stone.