To evaluate the safety, minimum effective dose (MED), pharmacokinetics and efficacy of orally administered 2',3'-dideoxy-2',3'-didehydrothymidine (d4T) in patients with AIDS or AIDS related complex (ARC). To establish an appropriate dosage regimen of d4T to be employed in Phase II and III trials. To evaluate the effects of de-escalating doses of d4T on markers associated with HIV infection.