The authors report a case of pregnancy in a patient suffering from moderately severe cystic fibrosis (the syndrome consisted of diffused obstruction in respiratory function with a vital capacity of 79% and the lowered blood oxygen level with arterial blood gas estimations; oxygen saturation was 94%). The condition was marked by temporary worsening during the pregnancy in which infective bronchitis supervened). She also threatened to go into early labour and did in fact deliver at 36 1/2 weeks of an infant which was normal for the duration of the maturity. The authors review previous known facts about cystic fibrosis. A study of the literature has made it possible to be more accurate in describing methods of ante natal diagnosis of the condition and ways of following the pregnancy and the illness as well as the woman's fertility and her ability to breast feed.