To determine the efficacy of Famvir 500mg bd as suppressive antiviral therapy for acute genital Herpes simplex virus (HSV) outbreaks in HIV subjects.

Inclusion Criteria:

• Able to provide signed informed consent
• Documented HIV infection
• In general good health, without other serious medical conditions as deemed by the investigator
• Male or female over 18 years of age
• Diagnosed genital HSV (clinical or laboratory)
• Life expectancy of 12 months or longer per investigator's judgment
• Stable on Famvir 500 mg bd for at least 30 days at time of screening

Exclusion Criteria:

• Pregnant or nursing (lactating) women, where pregnancy is defined as the state of a female after conception and until the termination of gestation, confirmed by a positive hCG laboratory test (>5)mIU/mL).
• Women of childbearing potential who are unwilling to use reliable contraception for the duration of the study.
• History of hypersensitivity to Famvir, its constituents or penciclovir
• Current use of another antiherpetic medication
• Recent history of alcohol or drug abuse, which in the opinion of the investigator may interfere with their compliance with study requirements, or who have any other conditions which in the opinion of the investigator would interfere with the successful completion of study procedures
• Disorder or condition that could interfere with drug absorption, distribution, metabolism or excretion
• Known or suspected to have or past history of renal dysfunction requiring a dosage modification of Famvir 500 bd

50-60 patients attending Holdsworth House Medical Practice in Darlinghurst, Sydney, New South Wales with documented HIV-1 infection who are taking Famciclovir 500mg bd as suppressive therapy for management of genital HSV infection who agree to participate in this study will be enrolled after signing HREC approved informed consent.