Introduction: Ensuring air quality in operation theatres is of paramount importance to prevent surgical site infections. Microbiological commissioning number of new surgical theatres in our hospital, has been a challenging, yet also a rewarding experience to our staff. Methodology: A total of 19 new operation theatres including orthopaedic, neurosurgical, and cardiac theatres and associated sterile site areas were evaluated. Air sampling was followed by high level cleaning and running ventilation systems for 25 air changes per hour. Five samples were collected from each operation theatre. A sample of 1000L of air was aspirated on to 5% Horse Blood agar over 10 minutes. Colonies were enumerated following aerobic incubation at 37◦C for 24 and 48 hours. Results: During the first round of sampling 73% of samples yielded satisfactory (≤10 CFU/m3) results. A second round of samples following deep cleaning was required to certify remaining theatres. Conclusion: Microbiological testing and commissioning of our new operation theatres enabled us to certify our new operation theatres locally.