Background: Surgical audits provide constructive feedback to individual surgeons, hospitals and other healthcare sector professionals. Audits identify deficiencies in treatment processes, evaluate practice trends and detect practice gaps. The credibility and validity of the Queensland Audit of Surgical Mortality (QASM) relies on the accuracy of its data. Methods: To determine the validity of routine reporting of surgical information to QASM, surgical case forms were compared against medical records (considered the gold standard). Data were extracted by a trained medical research assistant. QASM forensically reviewed 896 of a total of 5636 deaths in 20 Queensland public hospitals between 2008 and 2013. Concordance between the surgical case form and the relevant medical record was determined for 27 objective items. Results: Overall concordance was 98.2%. The median concordance was 100% (interquartile range 87–100%). Cases with discordance were few and in these, most had only one discordant item. Discordances were mainly omissions. Conclusion: The QASM surgical case form is a reliable data collection tool that provides high-quality data. QASM objective data can be confidently regarded as accurate and therefore reliable for use in publications, reports and case studies.