Primary hepatic leiomyosarcoma is a particularly rare tumor with a poor prognosis. Curative resection is currently the only effective treatment, and the efficacy of chemotherapy is unclear. This represents the first case report of a patient with primary hepatic leiomyosarcoma co-existing with metastatic liver carcinoma. We present a 59-year-old man who was diagnosed preoperatively with rectal cancer with multiple liver metastases. He underwent a curative hepatectomy after a series of chemotherapy regimens with modified FOLFOX6 consisting of 5-fluorouracil, leucovorin and oxaliplatin plus bevacizumab, FOLFIRI consisting of 5-fluorouracil, leucovorin and irinotecan plus bevacizumab, and irinotecan plus cetuximab. One of the liver tumors showed a different response to chemotherapy and was diag-nosed as a leiomyosarcoma following histopathological examination. This case suggests that irinotecan has the potential to inhibit the growth of hepatic leiomyosarcomas. The possibility of comorbid different histological types of tumors should be suspected when considering the treatment of multiple liver tumors. Primary hepatic leiomyosarcoma is a particularly rare tumor with a poor prognosis. This is the first case report of a patient with primary hepatic leiomyosarcoma co-existing with metastatic liver carcinoma We present a 59-year-old man who was diagnosed preoperatively with rectal cancer with multiple liver metastases. He underwent a curative hepatectomy after a series of chemotherapy regimens with modified FOLFOX6 consisting of 5-fluorouracil, leucovorin and oxaliplatin plus bevacizumab, FOLFIRI consisting of 5-fluorouracil, leucovorin and irinotecan plus bevacizumab, and irinotecan plus cetuximab. One of the liver tumors showed a different response to chemotherapy and was diag-nosed as a leiomyosarcoma following histopathological examination. This case suggests that irinotecan has the potential to inhibit the growth of hepatic leiomyosarcomas. The possibility of comorbid different histological types of tumors should be considered when considering the treatment of multiple liver tumors.