The cell line data base described in this paper includes both clinical information about the patients from whom the cell lines were derived and information about the in vitro analyses performed of the cell lines. The cell line data base has evolved as a part of a systematic effort by a research group at the NCI since 1976 to generate human cell lines as biological tools to study cancer and other diseases. The cell lines were generated from clinical specimens obtained as part of a series of Institutional Review Board-approved clinical protocols. The preponderance of the data is on lung cancer cell lines, though a broad range of other cancers are represented. A bank of over 300 human cell lines including cancer cell and in some instances autologous B-lymphoblastoid cells from the NCI-VA and NCI-Navy Medical Oncology Branch are reposited at the American Type Culture Collection. The cell lines are available for the research community. The entire data base is available on the American Type Culture Collection Web Site (WWW:http:@www.atcc.org/).