Twenty-two apparently healthy Nigerian adolescent girls aged 11–17 years residing in a hostel, were studied over five consecutive days in order to assess their energy intake (EI), energy cost of specific activities and body composition (BC). The mean characteristics of the group were: height 1·58 (SD 0·1, range 1·42–1·68) m, body weight 49·1 (SD 7·9, range 34·0–61·0) kg and BMI 19·5 (SD 2·0, range 16·0-23·0) kg/m2. The food intake of each subject was assessed by direct weighing and its energy value was determined by means of a ballistic bomb calorimeter. BMR values were calculated according to Food and Agriculture Organization/World Health Organization/United Nations University (FAO/WHO/UNU) (1985) equations. Percentage body fat (BF %) values were derived from three skinfold thickness measurements, using population-specific equations. The adolescents' mean daily EI was found to be 6510 (SD 855) kJ/d (138·3 (SD 27·8) kJ/kg body weight per d) which is lower than the FAO/WHO/UNU (1985) calculated energy requirement of 8800 kJ/d for adolescent girls aged 12–14 years. The contributions of specific nutrients and individual meals to the total EI were: carbohydrate, protein and fat, 59·2, 12·5 and 28·3 % of energy respectively and breakfast, lunch and supper, 21·5, 41·0 and 37·4 % respectively. However, the mean BMR was 5627kJ/d, which is comparable with that given by FAO/WHO/UNU (1985) for adolescent girls aged 13–14 years. The mean BF % was found to be 21·7. The comparatively low EI of the participants in the present study may be indicative of energy deficiency in their meals. This assumption is also reflected in their BC values. Nevertheless, further studies of this kind on adolescents in Nigeria are needed to confirm these observations.