Objective: This study aimed to estimate the incidence and characteristics of injuries caused by dogs and cats in the population of a major Italian city. Methods: The clinical records of all patients attending the emergency department (ED) were obtained from the two main hospitals of the city, covering an estimated population of over half a million. A case was defined as a patient admitted for bite or scratch injuries caused by dogs, cats, or other mammals between 1 January 2000 and 31 December 2002. For each case, the information collected included age and sex of the patient, the anatomical site of the injury, and the species of the animal involved. Results: The average yearly incidence of dog and cat bite/scratches was 58.4 and 17.9 cases per 100 000 residents, respectively. Admissions peaked during the summer months. Dogs accounted for 76.9% and cats for 19.7% of cases. Dog injuries were significantly more common in males and younger individuals. Children younger than 9 years had a significantly higher risk of being bitten on the head, face, or neck. Conversely, injuries from cats were significantly more common in females and older people. Conclusions: Surveillance of injuries caused by dogs and cats could provide useful information for planning and evaluating public health interventions. Collection of data from hospital EDs may be an appropriate, simple, and quick tool for monitoring the phenomenon and evaluating the associated risk factors.