One aim of the NIDEP study (nosocomial infections in Germany: surveillance and prevention) was to determine in part 1 (surveillance) the prevalence of nosocomial infections (NI) in patients in surgical departments of 72 representatively selected hospitals in Germany. The surveillance was carried out by four previously validated physicians who applied the CDC criteria for NI. The overall rate of NI was 3.8%. Urinary tract infections (1.45%) and surgical wound infections (1.34%) were the most common NI. The highest rate of wound infections was noted after amputations (7.2%), conventional appendectomies (4.1%) or operations on the colon or rectum (3.8%). The use of perioperative antibiotics varied widely depending on the kind of operation and was not in accordance with international guidelines in all hospitals.