BACKGROUND Cystic fibrosis (CF) is a hereditary condition in which lung disease affects all patients. In addition to pulmonary involvement, the multisystemic components of CF cause significant physical limitations. However, the impact of lung function on balance control in CF has not been studied. OBJECTIVE To assess body balance in adults with CF and to test its possible associations with lung function, nutritional status, and functional capacity. METHODS This was a cross-sectional study in which 14 adults with CF underwent pulmonary function testing (spirometry, body plethysmography, and carbon monoxide diffusing capacity (DLco), respiratory muscle strength, 6-min walking distance (6MWD), Berg balance scale (BBS), nutritional analysis (body mass index and bioelectrical impedance), and stabilometry. Body balance was quantified using stabilometry; all participants performed the following two trials: opened base, eyes open (OBEO); closed base, eyes closed (CBEC). RESULTS In stabilometry, the median for the lateral range and anterior-posterior range in the CBEC trial was 0.10 (0.08-0.11) and 0.13 (0.11-0.22), respectively (p<0.05). The maximal inspiratory pressure (MIP) correlated inversely with the lateral standard deviation (ρ=-0.61; p<0.05) as the DLco correlated positively with the anterior-posterior range (ρ=0.54; p<0.05). There were significant relationships between body composition indexes and almost all stabilometric variables measured. There were no relationships of the BBS and 6MWD with the stabilometric variables. CONCLUSIONS In adults with CF, imbalance occurs mainly in the anterior-posterior direction and is especially associated with body composition.