A case of acute renal failure probably associated with topiramate is discussed. The patient showed a significant, progressive increase in creatinine and serum urea values 5 days after topiramate treatment onset, as well as diminished creatinine clearance and non-oliguric acute renal failure requiring haemodialysis initiation. Upon topiramate discontinuance altered parameters became normal. No significant alterations were revealed by ultrasonography and renal biopsy. Coincidence in time and the absence of other factors suggest topiramate as likely cause of renal failure.