Patients undergo observation for 2 weeks, then are randomized to one of six treatment arms to receive ddI alone or in sequence or combination with AZT for 16-32 weeks, followed by 4 weeks of post-treatment evaluation. The regimens are: ddI alone for 32 weeks; AZT for 16 weeks followed by ddI for 16 weeks; AZT for 16 weeks followed by AZT/ddI combination for 16 weeks; ddI for 16 weeks followed by AZT for 16 weeks; AZT/ddI combination for 32 weeks; and placebo for 32 weeks.