BACKGROUND Through its patient safety programme «In safe hands,» the Norwegian Directorate of Health's objective is to ensure that the WHO Surgical Safety Checklist is used for all relevant surgical procedures. The purpose of this study was to investigate the recorded use of the WHO Surgical Safety Checklist, as well as to illuminate the factors that covary with its use, in order to be able to identify improvement measures.MATERIAL AND METHOD All surgical operations were reviewed at five surgical units at St Olavs Hospital Health Trust in three two-week periods in 2013. Recorded use of the checklist at each unit was compared to time of surgery, day surgery, acute or elective surgery and operating theatre time before, during and after surgery.RESULTS A total of 2297 operations were included. In 47 % of the operations, use of the entire checklist was recorded, in 31 % use of only parts was recorded and in 22 % no parts of it were recorded as having been used. The unit to which the patient belonged had the most bearing on the extent to which the checklists were used. A short time spent in the operating theatre, as well as operations that were classified in advance as acute, were associated with less recorded use.INTERPRETATION St. Olavs Hospital Health Trust has not achieved the objective of full implementation of the WHO checklist. There is considerable variation in recorded use at the units studied, and less recorded use of the checklist in the case of short and acute operations.