• The primary measure of acceptability will be defined as the proportion of women indicating that they would use the study product if it is found to prevent HIV. [ Time Frame: 3 months ] [ Designated as safety issue: No ]
• The primary measure of safety will be the proportion of women who have abnormal observations during the pelvic/speculum examinations and the proportion of women who experience adverse events [ Time Frame: 3 months ] [ Designated as safety issue: No ]

• The primary measure of acceptability will be defined as the proportion of women indicating that they would use the study product if it is found to prevent HIV.
• The primary measure of safety will be the proportion of women who have abnormal observations during the pelvic/speculum examinations and the proportion of women who experience adverse events

The proposed study is a multi-centre, open-label crossover study to assess the safety and acceptability of a silicone elastomer vaginal ring (containing no drug) when inserted for a 12 week period in 200 healthy, sexually active women.

• Experimental: vaginal ring first 12 weeks & observational safety last 12 weeks
• Experimental: observational safety first 12 weeks & vaginal ring last 12 weeks

Inclusion Criteria:

• Female, age 18-35 years
• Willing and able to provide written informed consent
• HIV-uninfected and otherwise healthy
• Self-reported sexually active
• On a stable hormonal contraceptive regimen
• Regular menstrual cycle
• Willing to refrain from use of vaginal products or objects during the study

Exclusion Criteria:

• Currently pregnant or last pregnancy within 3 months prior to enrollment
• Currently breast-feeding
• Participated in any other research study within 30 days prior to enrollment;
• Symptomatic untreated vaginal infections within 2 weeks prior to enrollment
• Presence of abnormal physical finding on the vulva, vaginal walls or cervix
• History of significant urogenital or uterine prolapse, undiagnosed vaginal bleeding, urethral obstruction;
• Pap smear result at screening that requires cryotherapy, biopsy, treatment (other than for infection), or further evaluation
• Unexplained, undiagnosed abnormal bleeding per vagina, bleeding per vagina during or following vaginal intercourse, or gynecologic surgery within 90 days prior to enrollment
• Any serious acute, chronic or progressive disease