We report the case of a liver abscess associated with microwave coagulation therapy (MCT). A 67-year-old man underwent a pylorus-preserving pancreatoduodenectomy for bile duct cancer in August 1998. In June 1999, abdominal computed tomography (CT) showed three low-density areas in his liver. With a diagnosis of multiple metastatic liver tumors, we applied MCT to each liver tumor. The patient presented with fever after therapy. Abdominal CT showed a hepatic abscess, which was treated by percutaneous transhepatic abscess drainage under ultrasonography. A bacteriological examination of the pus material revealed the presence of Enterococcus faecalis and Candida albicans. Treatment resulted in a rapid resolution of symptoms. Our case indicated that care should be exercised in using MCT for the treatment of liver tumors in patients who have undergone reconstructive surgery of the biliary tract.