Abstract Disclosure: M. Jung: None. M. Kim: None. Y. Choi: None. H. Yoo: None. S. Lee: None. E. Yoo: None. Purpose: Measurement of salivary cortisol is non-invasive and the level correlates well with that of free cortisol, but data in children are insufficient. We measured salivary cortisol and cortisone levels in obese children and compared with those in non-obese healthy children. Methods: A Total of 84 (45 obese and 39 non-obese) children aged 6 to 12 years were recruited. Children with acute or chronic illness were excluded. Salivary samples were analyzed for cortisol and cortisone using liquid chromatography-tandem mass spectrometry. Serum cortisol levels were measured only in obese children. Results: There was no significant difference in salivary cortisol and cortisone levels between the non-obese and obese children. There was no gender difference in salivary cortisol and cortisone levels. Salivary cortisol correlated to serum cortisol levels in obese children (ρ = 0.428, P = 0.007). Salivary cortisone levels were related with salivary cortisol (ρ = 0.537, P <0.001), and inversely with sampling time range (ρ = -0.282, P= 0.009). There was no significant correlations between salivary cortisol or cortisone values and age or body mass index. Conclusions: There was no significant difference in salivary cortisol and cortisone levels between non-obese and obese children. Salivary cortisol correlated well with serum cortisol in obese children. Presentation: 6/1/2024