The analyses in this paper indicate that redesigning injection equipment is unlikely to reduce the spread of HIV and may have other intended consequences. However, targeted distribution could be used to identify those situations in which: (1) injecting drug users would be least likely to try to defeat difficult-to-reuse equipment; (2) the cost, supply, and safe disposal problems would be manageable; and (3) use of difficult-to-reuse equipment would have the greatest impact on reducing HIV transmission among injecting drug users.