To assess the tolerance and toxicity profile of deoxy-3'-fluorothymidine (FLT) after multiple oral dosing for 16 weeks. To characterize the steady-state pharmacokinetics of FLT after multiple oral doses. To assess the effect of FLT on immunologic and virologic markers of HIV infection (CD4+ lymphocyte count, p24 antigen, viremia) in patients with AIDS or AIDS related complex (ARC) after multiple oral dosing for 16 weeks.