The prevalence of urinary tract infection (UTI) in 300 consecutively admitted, febrile, preschool children with and without a focus of infection was evaluated to determine the contribution of UTI to febrile illnesses. Uncentrifuged urine was evaluated by culture and microscopy. The prevalence of UTI was 9% and was significantly higher in girls than in boys. It was also significantly higher when urine infection had been clinically suspected than in those with other diagnoses. Temperature >41 degrees C and abdominal pain were significantly associated with UTI. Other features significantly associated with UTI were fever of at least 7 days duration, a peak evaluation temperature >or=38.3 degrees C and a white blood cell count >10/mm(3). Escherichia coli, Klebsiella pneumonia and Staphylococcus aureus were the only organisms isolated and they all showed high in vitro sensitivity to clavulanic acid-potentiated amoxycillin, gentamicin and ceftriaxone but were poorly sensitive to co-trimoxazole.