The HLA-B*27 allele is overrepresented in patients who control HIV-1 replication without antiretroviral therapy. CD8(+) T cell responses that target the immunodominant KK10 epitope in Gag are thought to play a major role in this control, and escape at R264 of KK10 is often associated with dramatic virologic breakthrough. We present a case in which an HLA-B*27-positive chronic progressor transmitted HIV-1 to an HLA-B*27-positive viremic controller who was temporarily on HAART, but who has since controlled viremia for over 4 years. We hypothesized that differences in the KK10 epitope of these patients would affect pathogenesis and viral fitness, but found no correlation between autologous KK10 mutations and disease progression or between the predicted fitness impact of autologous HLA-B*27-associated mutations and the actual fitness of autologous virus. This case of viral transmission between two HLA-B*27-positive individuals provides further evidence that prolonged control of fully pathogenic HIV-1 is possible.