We present the case of a 2-month-old infant presenting with pallor and laboratory results showing: hemoglobin 5.1 (10 to 1.5) g/dL, MCV 94.7 (75 to 105) fL, leukocytes 17.4 (7 to 15) ×10/μL, platelets 259 (150 to 450) ×10/μL, hyperbilirubinemia and renal dysfunction. A hemolytic anemia with tubular injury secondary to hemoglobinuria was suspected. Hyperhydration and packed cells were given but she deteriorated. Fluid overload with anuria further complicated the course necessating hemodialysis. Atypical hemolytic uremic syndrome was suspected and eculizumab was administered resulting in rapid improvement. Genetic analysis revealed a mutation in the gene encoding complement factor H and atypical hemolytic uremic syndrome was confirmed.