Introduction: Hemorrhagic cystitis (HC) is an infectious or noninfectious process that leads to gross hematuria originating from the urinary bladder mucosa.Case Report: A previously healthy 2.5-year old boy referred to our center five hours after ingestion of 120 mL (6 g) of cephalexin suspension with abdominal pain, diarrhea, vomiting and gross hematuria. The results of a general physical examination were unremarkable except for mild suprapubic tenderness. He was admitted to hospital and hydrated. Laboratory tests on admission showed a normal CBC and electrolytes, normal PT and PTT, negative coombs test, many RBCs per high-power field (HPF) in urine, and normal urinary tract sonography. Within 24 hours, the urine was cleared, showing only 1 to 2 red blood cells per high power field and no changes in CBC, electrolytes or kidney function tests. His urine culture was negative.Conclusion: Although there are reports of antibiotics- induced HC, the rarity of cephalosporines and cephalexin induced hemorrhagic cystitis encourage us to report this child.