Scientific evidence on needle exchange
Eight major, government-sponsored studies have concluded that needle exchange programs slow the spread of HIV among persons who inject drugs, and do not increase drug use.
Three former Surgeon General's have spoken out in favor or needle exchange programs: 

David Satcher, MD: Needle exchange programs can significantly reduce the spread of HIV. You do not deserve a death sentence because you're addicted.(1)

Joycelyn Elders, MD: Our best scientific research shows that needle exchange programs do not increase drug use, but do reduce the spread of HIV.  We need to speak out.  Silence about the importance of needle exchange programs is causing the deaths of thousands of our bright young black and Latino men and women. Time is slipping away.  Our bright young people are slipping away.(2)

C. Everett Koop, MD: When we are dealing with something as devastating as the AIDS epidemic, it doesn't matter what we do to reach people that have to be reached, we have to do it. … if clean needles will do anything to contain a part of the epidemic, we should not have any foolish inhibitions about doing so.(3) 
The American Medical Association, the American Public Health Association, and other medical associations have all called for government support of needle exchange programs.
Other relevant studies

Footnotes

(1) Lou Kilzer. "Satcher supports needle exchanges." Rocky Mountain News. November 6, 1999.  For highlights of Dr. Satcher's review of the literature on needle exchange, click here.

(2) Foreword by Dr. Joycelyn Elders to Dawn Day's report, Health Emergency 2001:The Spread of Drug-Related AIDS and Hepatitis C Among African Americans and Latinos.  

(3) New Jersey Lawyer. May 24, 1999. page 8.

For a list of other materials used on this website, see References.