Infection with the human immunodeficiency virus (HIV) usually leads to 8-10 years of asymptomatic infection before immune function deteriorates and AIDS develops. Without treatment, about 50% of infected people will die of AIDS over 10 years. With treatment, prognosis depends on age, CD4 cell count, and initial viral load.We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of preventive interventions? What are the effects of different antiretroviral drug treatment regimens in HIV infection? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2007 (BMJ Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).We found 17 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.In this systematic review we present information relating to the effectiveness and safety of the following interventions: combination treatments containing either CCR5 inhibitors or fusion inhibitors; early diagnosis and treatment of sexually transmitted diseases (STDs); early and delayed antiretroviral treatment using triple antiretroviral regimens; non-nucleoside reverse transcriptase inhibitor (NNRTI) based triple regimens; nucleoside reverse transcriptase inhibitor (NRTI) and protease inhibitor-based triple regimens (standard, and boosted); post-exposure prophylaxis in healthcare workers; and presumptive mass treatment of sexually transmitted diseases (STDs).