This press release discusses the decision to discontinue the tenofovir vaginal gel group in the VOICE (Vaginal and Oral Interventions to Control the Epidemic) HIV prevention trial. The decision came after a November 2011 routine review of study data collected from September 9, 2009, through September 30, 2011, concluded that tenofovir gel was safe but not effective in preventing HIV in the women enrolled in the trial. Further analysis of the data, released March 4, 2013, with the results of the VOICE trial, suggests that most of the women did not use the gel daily: tenofovir was detected in the blood samples of one-quarter of the study participants.