AIM: To describe the characteristics and outcome among patients suffering from in hospital cardiac arrest in relation to whether the arrest took place during office hours. PATIENTS: All patients suffering in hospital cardiac arrest in Sahlgrenska University hospital in Göteborg, Sweden between 1994 and 1999 in whom resuscitative efforts were attempted and for whom the time when the cardiopulmonary resuscitation (CPR) team was alerted. METHODS: Prospective recording of various factors at resuscitation including the time when the CPR team was alerted. Retrospective evaluation via medical records of patients previous history and final outcome. RESULTS: Among patients in whom the arrest took place during office hours (08:00-16:30 h) the overall survival rate was 49% as compared with 26% among the remaining patients (P