Information on food intake during weaning was collected as part of a mixed-longitudinal study on the nutritional status and growth of the 1985 Dutch birth cohort of infants on macrobiotic diets (n = 53) and a matched control group on omnivorous diets (m = 57). Weighed food records over 3d, including breast-milk, were obtained on 49 macrobiotic and 57 control infants at 2-monthly intervals between the ages of 6 and 16 months. Intake of energy and nutrients was calculated using the Dutch food composition table which was supplemented by our own analyses of 50 macrobiotic foods. Ninety-six per cent of the macrobiotic infants and 74 per cent of the control infants had been breast-fed, but breast-feeding continued longer in the macrobiotic group (13.6 vs 6.6 months, P less than 0.001). In the macrobiotic group, complementary feeding started at 4.8 months with water-based cereal porridges, followed later by vegetables, sesame seeds and pulses. Fruits were rarely given and products of animal origin were avoided. For all age groups combined, the intake of energy, protein, fat, calcium, riboflavin and vitamin B12 was significantly lower in the macrobiotic infants, whereas their intake of polysaccharides, fibre, iron and thiamin was higher than that of the control infants. The macrobiotic weaning diet tended to be bulky with a low energy density (2.4 kJ/g, controls: 3.4 kJ/g, P less than 0.05) and a high fibre content. Protein intake of the macrobiotic infants was only 80 per cent of the Dutch recommended daily intakes at the age of 6-8 months, and at 8 months, 69 per cent of this was derived from plant sources. Calcium intake was 280 mg/d; correction for calcium derived from hard tap-water raised the calcium intake to 308 mg in the macrobiotic age group of 14 months. The evidence of biochemical deficiencies of iron, riboflavin, vitamin B12, vitamin D and calcium is discussed. It is suggested that the macrobiotic diet should be supplemented with fat, fatty fish and dairy products.