Antiretroviral resistance in treatment-naïve patients with HIV-1 infection is on the rise in both resource-rich and resource-poor countries. We report a case of three-class primary antiretroviral resistance detected by a genotypic assay in a 19-year-old woman with acute HIV-1 infection. Her risk factor for HIV acquisition was unprotected sexual intercourse with a HIV-positive man. At diagnosis, her HIV-1 RNA level was 730,376 copies per milliliter, and 2 weeks later her CD4+ cell count was 465 cells/mm(3). The patient's antiretroviral therapy was chosen based on the genotype of the source patient. Subsequent analysis of our patient's virus revealed an identical genotype to that of the source patient. The patient tolerated therapy well and continues to be virologically suppressed after 1 year of therapy. Her current CD4+ cell count is 537 cells/mm(3) and HIV-1 RNA is less than 400 copies per milliliter. This case supports the current recommendations from several HIV therapy guidelines to perform resistance testing in patients with acute HIV-1 infection.