Abstract: Citrobacter, a member of the family Enterobacteriaceae, is usually present as intestinal commensal of man and animals. It is well known now that it has been associated with various nosocomial and community acquired infections in humans. This study was conducted in Department of Microbiology, J. N. Medical College and Hospital, Aligarh for a period of one and half years. Isolates were identified as Citrobacter and then till species level using O’Hara scheme. They were isolated in an overall prevalence rate of 2.1% with Citrobacter koseri and Citrobacter freundii as the most commonly isolated species in laboratory samples. Citrobacter was most commonly isolated from pus & urine in both the sexes with significant predominance in male population. It usually affects people of all age groups including extremes of age predominantly in adolescent and middle age.