Sickle cell disease (SCD) is associated with impaired growth and skeletal maturation. Decreased fat-free mass (FFM) and body fat (BF) have been reported in Nigerian children with SCD relative to healthy age- and gender-matched controls. Pulmonary abnormalities, including reduced forced vital capacity (FVC), forced expiratory volume in one second (FEV(1)) and total lung capacity (TLC), have also been described in children with SCD. Since undernutrition is common in sub-Saharan Africa, we were interested in knowing the relationship between pulmonary function and body composition in Nigerian children and young adults with SCD. Body composition was determined using bioelectrical impedance and pulmonary function was assessed by spirometry in Nigerian children and young adults aged 7-35 years (n = 102) as well as healthy age-and gender-matched controls (n = 104). Age-adjusted data revealed 19-26% lower FFM for male (P < 0.001) and female (P < 0.001) subjects with SCD relative to the controls. FVC, FEV(1) and PEF were also significantly reduced in male and female children and young adults with SCD compared to their control counterparts. For both male and female patients and controls, FVC, FEV(1) and PEF correlated positively with FFM (P < 0.001). PEF for the female subjects with SCD diverged progressively with increasing age relative to the controls and the rate of change was significantly lower (P < 0.001). We conclude that pulmonary function is reduced in Nigerian children and young adults with SCD compared to controls and that for both groups, pulmonary function is directly related to body composition. These findings underscore the need for early nutritional intervention for children with SCD.