Background: In 1999, the Institute of Medicine reported that, in the United States, 44,000 to 98,000 people die annually as a result of avoidable medical errors. Among the many initiatives undertaken to stem avoidable surgical errors, the World Health Organization (WHO) Surgical Safety Checklist has certainly been one of the most successful. Many surgical units have implemented adapted versions of the WHO Surgical Safety Checklist, audited their performance and discussed issues relating to the implementation process. However, such literature is still lacking in neurosurgery. Methods: A prospective observational study of 171 neurosurgical cases was conducted over an 8-week period. An independent observer assessed compliance with and completeness of the three steps in the perioperative checklist: Sign-in, Time-out and Sign-out. Factors that may reduce compliance were also analyzed. Results: Compliance with the Sign-in, Time-out and Sign-out steps was 82%, 99% and 93% respectively. On average, 92% of the Time-out elements were verified. The emergent nature of a surgery was the only factor that caused a statistically significant reduction in compliance with the checklist. Overall compliance diminished during the observation period. Conclusion: In this internal audit study, compliance with the preoperative checklist reached a satisfactory level. Further work is still needed, however, on some aspects of our surgical strategy, namely, a relatively low compliance rate with the Sign-in process was recorded and emergent cases were associated with decreased performance.