This study examined the prevalence of primary human immunodeficiency type 1 (HIV-1) drug resistance among recently infected youth in the United States. Of the 55 subjects studied, major mutations conferring HIV drug resistance were present in 10 (18%). Eight (15%) had nonnucleoside reverse-transcriptase inhibitor (NNRTI) mutations, with the majority (6) having the K103N mutation; 2 (4%) had nucleoside reverse-transcriptase inhibitor (NRTI) mutations; and 2 (4%) had protease inhibitor (PI) mutations. Phenotypic drug resistance was present in 12 (22%) subjects: 10 (18%) for NNRTIs, 2 (4%) for NRTIs, and 3 (5.5%) for PIs. The prevalence of primary HIV-1 drug resistance, particularly to NNRTIs, in this group of recently infected youth was high. © 2006 by the Infectious Diseases Society of America. All rights reserved.