Inclusion Criteria

Volunteers may be eligible for this study if they:

• Are female and 18-45 years of age.
• Are willing and able to complete daily study records.
• Are willing to undergo clinical exams and testing.
• Either have regular menstrual periods or do not menstruate due to use of hormones.
• Agree to stop using female barrier methods of birth control during the study.
• Additionally, volunteers may be eligible for HIV-negative groups in this study if they:
• Have not changed their use of hormonal birth control over the last 3 months.
• Are HIV-negative.
• Have a single male partner at low-risk for HIV infection and agree that he can be asked for his consent.
• Agree to the following: To have vaginal intercourse 2 or more times a week; to use condoms provided by the study for each act of intercourse; to use the gel as directed; not to be in similar studies; not to receive oral sex; not to use IV drugs, except for medical treatment; not to use any other vaginal products; not to douche; and not to use vaginal drying agents.
• Additionally, volunteers may be eligible for the HIV-positive group in this study if they:
• Are HIV-positive.
• Have a CD4 count greater than 200 cells/mm3.
• Have a normal Pap smear at screening.
• Are on stable anti-HIV drug therapy.
• Agree to have no sexual intercourse during the study.
• Have HIV care by qualified medical caregivers.
• Agree to allow study staff access to their HIV medical care information.
• Agree to the following: To use the gel as directed; not to use IV drugs other than for medical treatment; not to use any other vaginal products; not to participate in similar studies; not to receive oral sex; not to douche; and not to use any vaginal drying agents.

Exclusion Criteria

Volunteers will not be eligible for this study if they:

• Are menopausal.
• Have certain liver, kidney, or blood problems.
• Have genital problems such as sores.
• Are allergic to anything used in the study, including latex.
• Have used spermicides or condoms treated with spermicides within the week before enrollment.
• Have been in another drug study within the past 30 days.
• Have participated in this trial before and study gel has been permanently discontinued.
• Have had an IUD or begun using hormonal birth control, or had an abnormal Pap smear, a pregnancy, an abortion, gynecologic surgery, breakthrough menstrual bleeding, or vaginal bleeding during or following sexual intercourse, in the last 3 months.
• Have had or received treatment for sexually transmitted diseases in the past 3 months.
• Show signs, on a pelvic exam, indicating a sexually transmitted disease or other genital tract problems.
• Used IV drugs, except for medical reasons, within the past year.
• Received antibiotics in the last 14 days.
• Have had a reaction to an anticoagulant (such as warfarin or heparin).
• Are pregnant or breast-feeding.
• Have a positive urine culture.