BACKGROUND: The debate regarding 'When to Start' antiretroviral therapy has raged since the introduction of zidovudine in 1987. Based on the entry criteria for the original Burroughs Wellcome 002 study, the field has been anchored to CD4 cell counts as the prime metric to indicate treatment initiation for asymptomatic individuals infected with Human Immunodeficiency Virus. The pendulum has swung back and forth based mostly on the relative efficacy, toxicity and convenience of available regimens. DISCUSSION: In today's world, several factors have converged that compel us to initiate therapy as soon as possible: 1) The biology of viral replication (1 to 10 billion viruses per day) strongly suggests that we should be starting early. 2) Resultant inflammation from unchecked replication is associated with earlier onset of multiple co-morbid conditions. 3) The medications available today are more efficacious and less toxic than years past. 4) Clinical trials have demonstrated benefits for all but the highest CD4 strata (>500 cells/μl). 5) Some cohort studies have demonstrated the clear benefit of antiretroviral therapy at any CD4 count and no cohort studies have demonstrated that early therapy is more detrimental than late therapy at the population level. 6) In addition to the demonstrated and inferred benefits to the individual patient, we now have evidence of a Public Health benefit from earlier intervention: treatment is prevention. SUMMARY: From a practical, common sense perspective we are talking about life-long therapy. Whether we start at a CD4 count of 732 cells/μl or 493 cells/μl, the patient will be on therapy for over 40 to 50 years. There does not seem to be much benefit in waiting and there likely is significant long-term harm. Do not wait. Treat early.