Adenoid cystic carcinoma (ACC) is a rare malignant tumor of the head and neck occurring in the salivary glands. We established a human ACC line which is serially transplantable in nude mice and designated it as KOA-1. The KOA-1 tumor doubled in 9.3 days and retained the histologic characteristics of a solid pattern of ACC even after 22 serial passages. The KOA-1 metastasized to the lung 2 months after subcutaneous transplantation into nude mice. We further established a subline of KOA-1 by an in vivo selection method and named it KOA-1L3. The KOA-1L3 doubled in 1.3 days and metastasized to the lung within 1 week after subcutaneous transplantation. These tumor lines may serve as a useful model for exploration of the biological behavior and treatment of human ACC.