Proconvulsive tendency of imipenem/cilastatin is one of its well-known side effects. Most studies report incidence rates ranging from 1.5 to 3%. There is no study on the incidence rate among children with systemic malignancies. Eighty-two patients with various malignancies who received imipenem/cilastatin 143 times for neutropenic fever between March 1994 and October 1999 in Department of Pediatric Oncology, Gazi University, were identified. Three of these patients had convulsions attributed to imipenem/cilastatin; 3.6% of the patients had seizure, or 2 % of imipenem/cilastatin administrations was followed by a seizure attack.