Background: Caring for children with chronic medical illnesses (CMIs) can resulting in substantial out-of-pocket expenditure (OOPE) which can contributes to high caregiver burden(CB) Objectives: To describe OOPE incurred by caregivers of children with CMIs and to assess its association with caregiver burden. Methods: A cross-sectional study was conducted among 242 caregivers of children with CMIs (renal disease, uncontrolled epilepsy , thalassemia, diabetes, and asthma).attending pediatric units of three tertiary care hospitals in Kandy District, Sri Lanka. OOPE was assessed per hospital admission or clinic visit, including direct and indirect costs. CB was measured using Caregiver Burden Scale (CBS), with mean score >2 indicating higher CB. Associations between OOPE and CB were analyzed using univariate and multivariate logistic regression Results: Indirect costs exceeded direct medical costs with a median total OOPE of LKR 6000 per admission or clinic visit. More than half of caregivers (51.2%) experienced high OOPE. Overall, 33.5% of caregivers reported higher CB. OOPE was significantly associated with CB in univariate analysis (p=0.002). However, after adjustment for confounders, OOPE did not remain an independent predictor of CB. Longer hospital stays and having another child with a chronic illness (were independently associated with higher CB. Conclusions: Caregivers of children with CMIs incur substantial OOPE, mainly driven by indirect costs. Although OOPE was not an independent predictor of caregiver burden after adjustment, its high prevalence highlights the need for financial riskprotection strategies for families managing childhood chronic illnesses.