The genetic status of cyclin genes was examined in a panel of 47 colorectal carcinoma cell lines. Cyclin D2 was found to be amplified in one tumor and cyclin E in another. In each of the two cases, the amplified cyclin gene was overexpressed at the protein or mRNA level. Cyclin D1, previously shown to be amplified in breast and other tumors, was not amplified in these cancers. These data suggest that a variety of cyclin genes can play a role in human tumorigenesis and that cyclins D2 and E are particularly important in a subset of colorectal neoplasms.