This double-blind, placebo-controlled study is designed to determine the long-term safety and efficacy of concurrent oral Retrovir / Zovirax (AZT and ACV) therapy and oral AZT therapy alone, in the treatment of early symptomatic HIV infection. Efficacy will be evaluated by monitoring the incidence, severity, and time of development of opportunistic infections and other manifestations of advanced symptomatic HIV infection. The effects of the combination and single AZT therapy on immune function and viral replication will also be evaluated. Study participants will be monitored for evidence of toxicity or intolerance to concurrent AZT / ACV administration and AZT therapy alone.