AMENDED: Previously, rCD4-IgG had been administered on a mcg/kg basis. Subjects now receive rCD4-IgG as a fixed dose. Changes to the maintenance schedule were made to accommodate the new dosages. Original design: This study is divided into two parts: A pharmacokinetic evaluation, and a safety evaluation. The pharmacokinetic evaluation is done in selected patients. For the safety evaluation patients will receive rCD4-IgG at a fixed dose level twice weekly by intravenous bolus injection (over 1 minute) for 12 weeks. Zidovudine (AZT) is administered orally 3 times daily at one of two dose levels. Eight subjects, at least 4 of whom with p24 levels greater than 75 pg/m, are entered at each dose level of CD4-IgG beginning with dose level 1. If 3 or more patients at a dose level experience grade 3 or 4 toxicity then no further patients will be added to that or higher dose levels. Pharmacokinetics of CD4-IgG alone and in combination with AZT is evaluated in patients at dose level 2 only. Patients receive one IV bolus of CD4-IgG on day 1 and samples are drawn beginning 15-30 minutes prior to the CD4-IgG injection. There is an 8 day washout period. Beginning on day 9 and continuing through day 24, patients receive AZT daily. CD4-IgG is administered by IV bolus on day 16. Samples are drawn beginning 15-30 minutes prior to the injection of CD4-IgG. The pharmacokinetic evaluation terminates 8 days after the second CD4-IgG injection (day 24). Extended treatment will be made available to patients at the discretion of the Principal Investigator.