AbstractThe erythrocyte P, antigen was observed in 91.7, 70.6, 56.7 and 62.5%, respectively, of children with upper urinary tract infection, symptomatic and asymptomatic urinary tract infections and cases responsive to initial therapy in which the abnormal urinary findings disappeared with the administration of antibiotics given despite the absence of bacteriuria. These values were significantly high (P<0.001, 0.001, 0.01, 0.001, respectively) compared with healthy controls (29.0%).In cases where initial antibiotic therapy was effective despite no significant bacteriuria, the presence of Gal cd– 4 Gal receptor in large quantity on the surface of the mucosa of the urinary tract was suggested, just as in the typical case of urinary tract infection with bacteria in the urine.No significant difference was observed in the incidence of P1 antigen in the peripheral blood of sick children according to the clinical symptoms and urinary findings in typical cases of urinary tract infection and cases responsive to initial antibiotic therap