OBJECTIVE: This study aims to investigate the prevalence of health checkup attendance among Thai adults aged 19-60 years and the factors associated with participation in health checkups.METHODS: A cross-sectional study was conducted from October to December 2023 among 292 Thai individuals aged 19–60 years who received medical services at Vajira Hospital without prior appointments for chronic disease follow-up. Data were collected using a questionnaire comprising the following four sections: personal information, health-related and health checkups data, possible factors facilitating checkup attendance, and the reasons why non-checkup participants choose not to undergo health checkups. The factors associated with participation in health checkups were identified by multivariable logistic regression analysis with a significance level of 0.05.RESULTS: A total of 156 volunteers (53.4%) participated in checkups in the past 3 years. The factors associated with participation in checkups included earning more than 20,000 Baht per month (OR 3.06, 95% CI 1.12–8.41), checkups arranged by their workplace (OR 5.64, 95% CI 2.42–13.15), and encouragement by family or friends (OR 2.18, 95% CI 1.06–4.51). Underweight (OR 0.28, 95% CI 0.10–0.81) and overweight individuals (OR 0.23, 95% CI 0.08–0.64) were less likely to participate in health checkups than people with a normal body mass index. Lastly, individuals who could participate in checkups on weekends or holidays were less likely to do so than those unable to participate (OR 0.41, 95% CI 0.18–0.96).CONCLUSION: A portion of Thai adults aged 19-60 years still fails to attend health checkups. Health checkup utilization must be increased using various strategies, such as encouraging workplace-organized checkups and fostering peer encouragement, especially among low-income and underweight/overweight individuals.