Operation wounds and surgical wound infections (S.W.I.) in the surgical department of Holbaek County Hospital were recorded over a period of one year. This registration was conducted in co-operation with the National Centre for Hospital Hygiene to test a standardised and simplified registration system and edb-programme, the Danop-Data system, developed to record S.W.I. on PC. 1.377 wounds and 45 S.W.I. were recorded. The overall infection rate was 3.3%. This compares favourably with rates reported in more extensive foreign investigations. There were significantly fewer infections during the second six months than during the first six month of the year. This was not due to changed conditions during the period of registration. The registration system and the edb-programme provide a satisfactory method of continuous surveillance of S.W.I. At the same time, the system itself proved very easy to use.