The major risk factor for death in cystic fibrosis (CF) is a progressive lung injury; however, low nutritional status (NS) remains an important and underestimated problem in the management of these patients. The NS of a patient with CF is impaired by many factors, such as chronic malabsorption, pancreatic failure, chronic inflammation, and recurrent pulmonary infection – they all lead to higher energy demand in the presence of lower intake of nutrients. The NS of those with CF plays an important role in maintaining lung function. The patients with higher NS have longer life expectancies. According to the Russian National Registry, both pediatric and adult patients with CF have shorter life expectancies. The article discusses various nutritional support regimens and their impact on lung function parameters.