Human ribonucleases were purified from the sera of Hodgkin's disease patients by sequential column chromatography. The purified enzyme interacted with reverse transcriptase of Rauscher leukemia virus and formed an additive complex of Mr = 130,000. RNase and oligo(dG)-directed reverse transcriptase activities were diminished in the complex. The complex could be dissociated with the subsequent restoration of both activities in the presence of spermidine. The molecular weight of the complex suggest that the 2 RNase molecules bind to a single reverse transcriptase molecule.