Sterile cerebrospinal fluid pleocytosis occurs in febrile infants with urinary tract infection. Coinfection with enterovirus is a possible cause. We evaluated 57 infants with urinary tract infection and cerebrospinal fluid pleocytosis. All had enterovirus testing by polymerase chain reaction. An explanation for pleocytosis was determined for 24 infants (42%). Enterovirus infection was detected in 4 and is an uncommon cause of cerebrospinal fluid pleocytosis in infants with urinary tract infection.