Background: Cystic fibrosis (CF), previously considered rare in Sri Lanka, demonstrates substantial clinical and CFTR mutational heterogeneity . We describe the demographic, phenotypic, and genotypic characteristics of Sri Lankan patients, Methods: Thirty-six patients with confirmed CF, followed by paediatric pulmonologists were studied. Diagnosis was based on characteristic clinical features, elevated sweat chloride levels, and identification of pathogenic CFTR variants. Clinical and genetic data were extracted from medical records, and descriptive statistics were applied. Results: The male-to-female ratio was 20:16. Median age at diagnosis was 4 years (IQR 3–8), with the oldest and youngest diagnosed at 35 years and 6 weeks respectively . Median current age is 11 years (IQR 5–15). Ethnic distribution was Sinhala 33% (12/36), Tamil 11% (4/36), and Muslim 55% (20/36), with consanguinity frequently observed among Muslims. Recurrent chest infections and malnutrition were the commonest presenting features. Pseudo-Bartter syndrome led to diagnosis in 11% (4/36). Bronchiectasis was identified in 58%. Pancreatic insufficiency was present in 69% (25/36), whereas CF-related diabetes and liver disease were uncommon. Pseudomonas aeruginosa colonisation occurred in 41% (15/36). All patients had positive sweat chloride tests. CFTR genotyping, available in 23 patients, showed 48% (11/23) compound heterozygosity . ? F508and the rare variant c.2738A>G (p.Tyr913Cys; Y913C) were each detected in 26% (6/23). Eleven patients were eligible for CFTR modulator therapy , anticipated locally this year Conclusion: Sri Lankan patients with CF exhibit marked phenotypic and genotypic diversity , delayed recognition, and limited access to advanced therapies, highlighting the need for improved access to CF-specific treatment in resource-limited settings.