The National Institutes of Health has granted a worldwide license for 2'-fluoro-2',3'-dideoxyadenosine (F-ddA) and 2'-fluoro-2',3'-dideoxyinosine (F-ddI) to U.S. Bioscience, Inc. (West Conshohocken, PA). NIH intentions to grant this license and further information about these drugs were reported in the June 1994 Bulletin (p. 174). F-ddA and its metabolite, F-ddI, are acid-stable inhibitors of HIV reverse transcriptase with efficacy in SCID mice comparable to that of AZT. F-ddA has not demonstrated cross-resistance to AZT, DDC or DDI and is synergistic with AZT. Clinical trials will be conducted in collaboration with NIH, most likely through a Collaborative Research and Development Agreement (CRADA).