Cystic fibrosis (CF) is the most frequent genetic disorder occurring in Caucasian, followed to preterm death. Clinical diagnosis of CF is set in infant or early childhood. Late diagnosis of CF is most often caused by non-typical course of the disease, rarely by misdiagnosis and not taken CF into account in differential diagnosis. In this paper we present two cases of misdiagnosis lung and digestive symptoms, treated as asthma bronchiale.