The present study examined whether infants show an acceptance for extreme sour tastes and whether acceptance of sour taste is related to infants' fruit intake. Fruit intake of fifty-three infants at 6, 12 and 18 months was assessed using 3 d food records. Sour acceptance of these infants was studied at 18.1 (SD 1-5) months. Acceptance for four solutions differing in citric acid concentrations (0-00 M, 0.013 M, 0.029 M and 0.065 M) was measured by allowing infants ad libitum ingestion of each solution over brief time periods. The base solution to which citric acid was added was blackcurrant squash diluted in water. Infants' relative intake of each solution was used as a measure of sour acceptance. At 18 months, twelve infants readily accepted the two highest citric acid concentrations, whereas the remaining infants rejected these. Infants who accepted the most sour solutions had a significantly higher fruit intake (P=0.025) and a higher fruit variety (P=0.015) at IS months than the infants who rejected the highly sour taste. Furthermore, infants who accepted the most sour solutions consumed fruits more frequently at 18 months (chi(2) 5.1; P=0.024). Infants who accepted the sourest solutions also had a higher fruit intake at 6 months, and a significantly higher increase in their fruit intake from 12 to 18 months. This is the first scientific study that demonstrates the acceptance of sour tastes in some infants at the age of 18 months. Furthermore, the present results suggest a relationship between acceptance of sour tastes and infants' fruit intakes.