Fever is a common complaint in infancy, and bacteraemia is one of the more serious causes of such fever. However, there exists scanty data on risk of bacteraemia among febrile infants of developing countries and what clinical predictors, if any, could identify those febrile infants with bacteraemia. To address this issue, 102 infants aged 1-12 month(s) attending the Children's Emergency Ward of University College Hospital, Ibadan, Nigeria, with rectal temperatures of>> or = 38 degrees C and with a negative history of antimicrobial use for at least one week prior to presentation, were studied to identify clinical predictors of bacteraemia. Infants, meeting the eligibility criteria of the study, underwent a full clinical evaluation and had blood cultures done for aerobic organisms by standard methods. Over 38% of the infants had bacteraemia. Escherichia coli (35.9%), Staphylococcus aureus (33.3%), and Klebsiella spp. (10.3%) of positive cultures were commonly isolated. Three variables, age of < or = 6 months, restlessness, and a white cell count of >15,000/mm3, were significant independent predictors of bacteraemia. Each of these variables was associated with a 3-6-fold increase in risk of bacteraemia (age of < or = 6 months: odds ratio 3.2, p = 0.017; restlessness: odds ratio 6.3, p = 0.019; and white cell count of >15,000/mm3: odds ratio 5.4, p = 0.024). The variables, in combination, correctly classified 70% of the infants into 'bacteraemia' or 'no bacteraemia'. It is concluded that; in the setting of the study, about 4 in 10 febrile infants would have a positive blood culture for aerobic organisms and that age of < or = 6 months, restlessness, and a white cell count of>> or = 15,000/mm3 are associated with a significantly increased risk of bacteraemia. Clinicians practising in such a setting need to be aware of the increased risk of bacteraemia in infants with these clinical features.