A case of acute acalculous cholecystitis in a ten-year-old boy presented with perforation of the gallbladder under antibiotic therapy. A biliary peritonitis secondary to gallbladder perforation was observed during laparotomy, and cholecystectomy was performed. Except mild hyperbilirubinemia, his postoperative period was uneventful. After investigation, Crigler-Najjar syndrome type 2 was detected and phenobarbital therapy was started. Both perforation of the gallbladder and Crigler-Najjar syndrome are uncommon diseases in childhood, and occurrence of these two diseases together was not previously reported in English-language literature.