RESUMEN
Prognosis of cystic fibrosis has been largely modified over the past 30 years. Optimization of nutrition is one of the most important contributing factors of this improvement. Nutritional defect result from the conjunction of loss of calories, maldigestion, hypercatabolism and insufficient intake. Pancreatic opotherapy and ADEK vitamin administration is mandatory in pancreatic insufficient patients. Nutritional status must be evaluated at each clinics to detect nutritional defect as early as possible. Nutritional intake must be hypercaloric, normalipidic and adapted to the tastes of the patient. The clinician must be aware of at risk nutritional period: first year of life, puberty, infectious exacerbation, respiratory worsening and diabetes, In neonatal screened babies, recovery of birth weight percentile must be targeted at 6 months, and for the height must be in accordance to genetic height at 2 years. In all cases it is mandatory to treat denutrition by oral supplementation and if necessay enteral nutrition.