This study analyzes the effective patent life of antiretroviral (ARV) new molecular entities (NMEs) approved for marketing in the United States (US) between 1987 and 2007. The study includes all NMEs approved during the study period with at least one patent listed in the Orange Book (OB). Drugs discontinued from the market were excluded from the analysis. Data sources are the US Food and Drug Administration (FDA) and the US Patent and Trademark Office. A comparison between the effective patent life of ARV NMEs and NMEs from other therapeutic classes was performed. The first and last patents were used to estimate the minimum and maximum effective patent life of NMEs. Group differences were assessed using group comparison t-tests, Chi-Square and Fishers' exact tests. The FDA approved 547 NMEs during the study period; 153 NMEs did not have a patent listed in the OB or were discontinued from the US market. The patent analysis included 22 ARV NMEs and 372 other NMEs. ARV MNEs had a range from 1 to 15 patents listed in the OB. The FDA new drug application (NDA) review time was shorter for ARVs (5.8+/-2.3 months) than for other NMEs (23.6+/-18.7 months). ARV NMEs had an average of 13.2+/-3.8 years of effective patent life for the first patent versus 11.0+/-4.2 years for other NMEs. ARV NMEs had an average of 17.5+/-3.6 years of effective patent life for the last patent versus the 14.8+/-4.8 years for other NMEs. The effective patent life listed for the last patent of seven ARV NMEs (31.8%) exceeded 20 years. Shortening the drug approval process increased the effective patent life of ARVs and facilitated faster entry of new drugs into the market. ARVs had an average of 2-3 more years of effective patent life than other therapeutic classes and, therefore, a longer period without generic competition.