P>Clostridium difficile infection (CDI) is a growing concern with regard to increases in incidence and its associated financial burden. A retrospective analysis of patients admitted to Hospitals in Edinburgh from 2003 to 2007 and tested for C. difficile toxins was performed. A total of 45 412 faecal samples were tested and 6286 (13.8%) were positive. Overall CDI was identified in 1.7 cases/1000 in-patient occupied bed days (OBD). The incidence of CDI fell from 1.98 cases/1000 OBD in 2006 to 1.48 cases/1000 OBD in 2007. Renal Medicine, including Transplant Surgery, and Intensive Care had the highest incidence, with > 6.2 cases/1000 OBD each, followed by Infectious Diseases and Gastrointestinal Medicine, with rates of 5.5 and 4.42 cases/1000 OBD, respectively. Medicine of the Elderly had an incidence of 1.69 cases/1000 OBD. Incidence increased with age, from 0.45 cases/1000 OBD in the 0-20-year-old age group to 2.02 cases/1000 OBD in the 61-80-year-old age group. Twelve percent of all toxin-positive patients were transferred through a minimum of two specialties when they remained positive for C. difficile toxins. Estimated costs over the study period for toxin testing were approximately 126 pound 500 and the minimal potential hospitalization costs for patients with CDI was 20 pound 000 000. The overall incidence of patients identified with CDI fell in 2007 compared to 2006. The incidence has increased with age; however, patients in Medicine of the Elderly had a much lower incidence than in several other specialties and therefore risk assessment of CDI should also be targeted within other specialties. Judicious application of infection control measures remains important for preventing CDI.