Summary: This study assessed the impact of enfuvirtide on health-related quality of life (HRQoL). Patients enrolled in 2 phase 3 trials T-20 versus Optimized Regimen Only (TORO 1 and 2) completed the Medical Outcomes Study (MOS)-HIV questionnaire at baseline and at 4, 8, 16, and 24 weeks. A total of 995 treatment-experienced HIV-1-infected individuals received either self-administered enfuvirtide (90 mg twice daily) + optimized background (OB) or OB alone and had at least 1 follow-up visit. Data from the 2 clinical trials were pooled. Analysis of covariance was used to evaluate changes in the 10 MOS-HIV scale scores and 2 summary scores. Least-squares means for these changes were calculated and used to test for between-group differences. There were no significant between-group differences in any HRQoL measure at baseline. Most MOS-HIV scores showed improvement in the enfuvirtide arm compared with OB alone, although only some of these were significant. Improvements in the general health scale were significantly higher in the enfuvirtide arm compared with OB alone at all post-baseline time points. No scale or summary score for the OB arm showed a significantly greater improvement in score from baseline compared with the enfuvirtide arm, at any time point. The mental health summary score at 24 weeks was significantly higher in the enfuvirtide arm compared with OB alone. Enfuvirtide in addition to an OB regimen does not adversely affect and may improve HRQoL when self-administered for up to 24 weeks by treatment-experienced, HIV-1-infected individuals.