The Drosophila melanogaster clone list is a data base describing information about cloned DNA from known chromosome regions. Currently over one quarter of the unique sequences in the Drosophila genome have been cloned; the data base keeps track of these locations so that other workers can find starting clones for their own cloning walks or can relate cloned genes to new mutations. The clone list also maintains records on which of the genes have been sequenced, transcripts described, or regulatory regions described by promoter fusion studies. Each record includes information on cloning method, vectors, and sizes of genomic and cDNAs. Items for fast retrieval and cross referencing, such as key words on homology domains, gene names, GENBANK/EMBL acquisition numbers and MEDLINE import match numbers are included. Citations are acquired from MEDLINE and CURRENT CONTENTS and personal communications. A summary of the clone list is published in the Drosophila information service, Genetic Maps, and is on line at the Indiana University Bio Computer. We propose to continue and expand this catalog as new data are generated. We propose to place the entire data base on line with the University of California Melvyl system for browsing access.