Intrahepatic cholangiocarcinomas that secrete macroscopically excessive mucin into the biliary system are rare, and few of the previously reported cases have achieved a curative resection. We defined these tumors as “mucin-producing intrahepatic cholangiocarcinomas” and clarify the optimal preoperative and surgical management for them. Eleven patients with mucin-producing intrahepatic cholangiocarcinomas underwent surgical resection in our department. The clinical, radiologic, surgical, and pathologic findings were studied. The clinical presentation of the 11 patients included repeated abdominal pain, jaundice, and fever. Conventional cholangiographies, such as percutaneous transhepatic cholangiography or endoscopic retrograde cholangiography, could not offer precise information about tumor location and extension because of abundant mucin in the biliary system. Using percutaneous transhepatic biliary drainage (PTBD) and percutaneous transhepatic cholangioscopy (PTCS), we were able to drain the mucin and determine precisely the cancer extension into intrahepatic segmental bile ducts. Based on these findings, various types of liver resection with or without extrahepatic bile duct resection were planned, and 10 patients obtained curative resection. The cumulative 5-year survival rate after curative resection was 78%. In patients with mucin-producing intrahepatic cholangiocarcinoma, PTBD and PTCS are important for evaluating the cancer extension. Rational surgery based on accurate preoperative diagnosis improved the prognosis of patients with this disease.