Decision-making in daily unit operation in perioperative settings needs to be smooth. Decision support systems are mainly used as help in this situation. These systems reduce the possibility of risks caused by poor communication. But the decisions and dimensions of the decisions made by nurse manager are still unsolved. The aim of our study was to describe the timeframe of the decisions made by nurse managers in the daily unit operation in perioperative settings. The results indicated that nurse managers made operational and tactical decisions. These operational and tactical decisions happened coincide during the nurse managers shift. The nurse managers were repeatly interrupted in decision-making.