To trace the growth of syringe exchange programs (SEPs) in the United States since 1994-95 and assess the current state of SEPs. Annual surveys of US SEPs known to North American Syringe Exchange Network (NASEN). Surveys mailed to executive directors with follow-up interviews by telephone and/or e-mail. Response rates have varied between 70% and 88% since surveys were initiated in 1996. The numbers of programs known to NASEN have increased from 68 in 1994-95 to 186 in 2007. Among programs participating in the survey, numbers of syringes exchanged have increased from 8.0 million per year to 29.5 million per year, total annual budgets have increased from 6.3 to 19.6 million US dollars and public funding (from state and local governments) has increased from 3.9 to 14.4 million US dollars. In 2007, 89% of programs permitted secondary exchange and 76% encouraged it. Condoms, referrals to substance abuse treatment, human immunodeficiency virus (HIV), hepatitis C virus (HCV), hepatitis B virus (HBV) counseling and testing and naloxone for overdose were among the most commonly provided services in addition to basic syringe exchange. Each of these services was provided by 40% or more of SEPs in 2007. While syringe exchange has remained controversial in the United States, there has been very substantial growth in numbers of programs, syringes exchange and program budgets. Utilizing secondary exchange to reach large numbers of injecting drug users and utilizing SEPs as a new platform for providing health and social services beyond basic syringe exchange have been the two major organizational strategies in the growth of SEPs in the United States.