Once the genetic defect of cystic fibrosis (CF), the most common autosomal recessive disease, was discovered, there was hope for quick positive results with gene-therapy. These did not came true, however. Recent CF mice studies by Freedman et al. demonstrated a disease reversal by high doses of docosahexaenoic acid (DHA). Although it is known for long that the same essential fatty acid imbalance with low levels of DHA is present in CF patients and that DHA has antiinflammatory actions, caution is urged to prevent false expectations when we extrapolate mice model results. This review explores the present scientific data on DHA supplementation in CF.