Introduction celiac disease (cd) and cystic fibrosis (cf) are common causes for chronic intestinal malabsorption in childhood and could present similar. Last known prevalence in the netherlands is about 1:4750 for cf and 1:200 for cd. In case of co-occurrence, one of both could be easily missed.patients and methodsin three university hospitals in the netherlands 140 cf patients under the age of 18 years with intestinal malabsorption underwent serological screening for cd with immunoglobulin a (iga) against tissue transglutaminase (ttg) and/ or endomysium (ema). Outcome of investigation and further research were extracted. Number of cd patients under the cf patients was determined.results15 of the 140 examined children expressed high ttg and/ or ema iga. In total 10 patients retrieved an intestinal biopsy. Cd was diagnosed in 7 children.discussiona result of 7 out of 140 (1:20) cd patients under children with cf was yielded. Comparison with the last known cd incidence in the netherlands (31:6127 (1:198)) provides a strong suggestion that a relation between both diseases exists. To conclude true incidence more research is necessary.conclusionco-occurrence of cd and cf in our study population is more often than expected from known prevalence numbers. In our opinion it is essential to screen for cd in case of cf to provide appropriate care for nutrition.