This study aimed to evaluate intraoperative interruptions by frequency, type, interference and source, and preventive measures. The interruptions in the operating theatre were evaluated for 52 surgical procedures based on real-time recordings and divided into routine operative procedures (ROP, n = 26, without intervention) and intervened operative procedures (IOP, n = 26, observed after team brief and placement of a warning sign for unnecessary door openings) groups. Intervened operative procedures vs. routine operative procedures was associated with a significantly lower number of interruptions (p = 0.014). Implementation of preventive measures was associated with a significantly lower number of entrances and exits (p = 0.001) and equipment issues (p = 0.003), interruptions that affected the circulating nurse or anaesthesia technician/associate (p = 0.003) and those caused by team members other than assisting surgeon and scrub nurse (p-value ranged from 0.015 to 0.009). Our findings revealed significantly reduced interruptions after a simple preventive measure including team brief and the placement of a warning sign for unnecessary door openings.