CF NBS in Poland started in 2006, the Warsaw CF Centre being responsible for 25% of the population (over 100,000 births a year).The screening protocol is based on IRT/DNA analysis, covering the 15 most common mutations as well as over 300 of the less common using sequencing technology.Among the 43 infants disgnosed were 10 with meconium ileus -MI (only 2 did not have increased IRT values).The average age of diagnosis was 46.6 days.Both mutations were known in 38 out of 43 infants.The most common were F508del homozygotes (44, 2%) and F508del heterozygotes (32.6%).In 5 patients only 1 mutation was found.Among MI infants 60% were F508del homozygotes.The average sweat test values were 68.9%.In 2 children sweat test values were lower than 40 mmol/l.There were 8 children who at the time of diagnosis were symptom free, 5 presented respiratory symptoms, 5 both: respiratory and gastrointestinal (GI), and 25 only GI syndroms (MI, steatorrhea, hiperbilirubinemia, worse somatic development).30% of the patients were pancreatic sufficient.There were no radiological changes at x-ray on diagnosis.In 4 children Pseudomonas aeruginosa colonisation was confirmed in the first year of life. Conclusions:1.In most of the CF infants GI symptoms were observed at the time of diagnosis 2. Most of hte MI infants had increased IRT values and were detected through the normal screening protocol 3.In screened newborns positive sweat test should be established at 30 mmol/l 4. A larger spectrum of mutations enables diagnosis of CF even in infants with normal sweat tests.