This is a retrospective analysis of 19 babies born with biliary atresia (12 girls, 7 boys) who were treated at the Hospital das Clínicas of the Ribeirão Preto Medicine School. The portoenterostomy operation was performed in 16 patients. All operations were performed before 12 weeks of postnatal life. Diagnostic laboratory studies are discussed. The authors conclude that the cholestatic jaundice protocol employed proved to be very necessary, can lead to early diagnosis can improve survival.