In a prospective study of 180 children admitted consecutively to King Edward VIII Hospital, bacteriuria (BU) was detected in 47 (26%), associated with pyuria in 35. BU occurred in association with other common childhood diseases in all but one child: acute lower respiratory tract infection (LRTI) in 43%, gastro-enteritis (GE) in 34% and protein energy malnutrition (PEM) in 26%. Conversely, BU was detected in 24% of children with LRTI, 33% with GE and 38% with PEM. Children with or without BU thus presented with similar symptoms and signs, except for vomiting and dehydration which were more frequent in those with BU. The male:female ratio was higher in BU under 2 years of age. Localizing urinary tract symptoms and signs were infrequent. Only one of the 35 children in whom ultrasonography was performed showed structural defects. The organisms detected (mainly Escherichia coli) were resistant to commonly used antibacterial drugs. There was a high specificity for dipstix testing, but low sensitivity, possibly because of sampling by catheter. There were seven deaths, three with and four without BU. Other illnesses contributed to death in all cases. Our findings have implications for the management of children who are hospitalized for common diseases in developing countries. It is not clear whether pyuria and BU were transient or indicative of serious disease of the kidney and urinary tract.