Cystic fibrosis (CF) is a monogenic autosomal recessive disease. Although several organs are affected, severe lung disease is the cause of most morbidity and mortality in CF individuals. The first clinical trials in CF patients were carried out in 1993, and to date, 29 trial protocols have been published. Although proof-of-principle for gene transfer to the lung has been established, efficiency is generally low. Steady progress has been made over the last two years and key papers, including recent advances in viral and nonviral gene transfer agents, will be reviewed here.