To determine the toxicity of low dose foscarnet administered for 4 weeks to HIV infected patients who are asymptomatic, have AIDS, or other HIV associated conditions and a CD4+ lymphocyte count < 500 cells/mm3. To obtain preliminary efficacy data. Although zidovudine (AZT) has been effective in treating some AIDS patients, AZT has toxic effects in many patients and other means of treating HIV-infected persons need to be evaluated. In vitro (test tube) studies have shown that the human herpes viruses are inhibited by foscarnet and that a number of retroviruses, including HIV, are sensitive to it. It is hoped that treatment of HIV-infected individuals with foscarnet during an early phase of HIV infections will reduce the risk of developing AIDS.