Children in northern Nigeria and elsewhere in the hot, arid western Sahel, are at risk of having their lung function compromised by a variety of factors, including undernutrition, environmental factors (e.g. airborne pollutants such as dust and smoke from wood fires), chronic upper-respiratory tract infections, and low socioeconomic class. We were interested in using spirometry to compare the pulmonary function of Nigerian children and adolescents aged 6-18 years who were living in urban and rural settings with the corresponding standards for African-American children. A total of 183 boys and girls in the rural village of Sabon Fobur on the Jos Plateau and another 128 boys and girls in the city of Jos were tested to determine their forced vital capacity (FVC), FVC at 1 s (FVC1), and peak expiratory flow (PEF). The nutritional status of the subjects was determined by measuring the body mass index (BMI), triceps skin-fold thickness, and mid-arm circumference, and fat-free mass (FFM) and fat mass (FM) by bioelectrical impedance analysis. According to the results of anthropometry, the subjects in Sabon Fobur and Jos were lean but generally adequately nourished. The mean FVC, FVC1 and PEF values for the rural males were 1.851,1.761, and 3.521, and for the urban males they were 1.971,1.791, and 3.471, respectively. The corresponding values for the rural females were 1.791,1.701, and 3.371, and for the urban females they were 1.761,1.671, and 3.091. These values were approximately 100 per cent of the corresponding values for African-American children. In general, strong correlations were found between each of the three lung function parameters and age, weight, height (only for the males), BMI, MAC, and FFM. These results show that: (1) the lung function of Nigerian children and adolescents living in either rural or urban areas were similar and compared favorably with African-American standards, and (2) weight was as important as height in determining pulmonary function. The inclusion of FFM as an explanatory variable did notfurther increase the accuracy of the prediction, even in a population where malnutrition may be prevalent. Therefore, we conclude that measurements of height and weight are all that are required for the assessment of lung function using spirometry in Nigerian children.