 This systematic review examined the accuracy of case identification methods used to select individuals with obesity from healthcare administrative databases. The results showed that ICD codes were the most commonly used method, but its accuracy varied greatly depending on the study. Overall, the sensitivity of these methods was low while the specificity was higher. This suggests that case identification methods may not be reliable for monitoring the prevalence and incidence of obesity within healthcare administrative databases. However, they remain useful for selecting individuals with obesity for cohort studies, especially those with severe obesity or those who have obesity as part of a comorbid condition. This article was authored by Seko Samadalagu, Liana Dzerda, Roxanne Dalt, and others.