We have recently reported that ascitic cells from a human ovarian carcinoma have a 10- to 20-fold K-ras amplification and that the level of such amplification did not change over a 9-month period during which the patient received chemotherapy and underwent clinical progression. Here we describe an ovarian tumor cell line (HOC-8) which has been derived from that tumor and which also shows a similar level of K-ras amplification. The amounts of K-ras specific mRNA and the Mr 21,000 protein encoded by the amplified gene are correspondingly elevated. karyotypic analysis revealed no detectable double minute chromosomes but did show an abnormal banding region on chromosome 6. This cell line may represent a useful model to investigate the significance of the K-ras gene product for the pathogenesis of human tumors.