Cystic fibrosis is a recessive disease that causes changes in mucus secretions, affecting different systems: respiratory, digestive, pancreatic, hepatic; resulting in obstructions and secondary infections. Transplantation may be used for the most severe forms and is then complicated by the pediatric context, the existence of malabsorption and secondary infections and the type of transplantation (pulmonary and/or hepatic). The follow-up is characterized by pulmonary infections and pulmonary chronic rejection. In our experience, the initiation of the immunosuppressive treatment must avoid corticoids in the early post-transplantation days and have recourse to intravenous cyclosporin (CyA) 2 mg/kg/day, given on average for one month in an oral form. In case of persistent acute rejection, tacrolimus (FK 506) is instituted. Oral CyA (10-12 mg/kg/day) seems more sensitive to malabsorption syndrome than FK 506 (0.2 mg/kg/day). In both cases, the development of an inhibitory metabolic interaction in the presence of itraconazole must be taken into account: used against aspergillosis, itraconazole is metabolized as CyA and FK 506 by Cyt P450 3A4. The intensity of the interaction is twofold for CyA versus fivefold for FK 506. The strategy for the use of other recently available immunosuppressives such as mycophenolate is under evaluation.