High molecular natural (ridostin and larifan) and synthetic (camedon) interferon inducers inhibited HIV-1 replication in MT-4 and CEM cultures when administered simultaneously with the inoculum. The effect of interferon inducers was comparable with that of azidothymidine in concentrations providing cell protection. The degree of culture protection determined by the number of viable and antigen-containing cells was approximately similar for strain 899A and freshly isolated IV39. No significant difference in the efficacy of the preparations in the two different cell cultures. MT-4 and CEM, was observed. It may be assumed that the antiviral effect of the interferon inducers under study will depend little on the type of cell culture.