The sorption capacity of the dye cibacron blue F3GA, immobilized on CL-Sepharose 6B and other support matrices, in respect to DNA- and RNA-ligases T4 was being studies. Cibacron blue F3GA immobilized on CL-Sepharose 6B binds a three-fold amount of DNA-ligase in comparison to RNA-ligase. The enzyme chromatography on cibbacron blue F3GA-CL-Sepharose 6B revealed a stronger linkage between DNA-ligase T4 and the sorbent than between RNA-ligase T4 and the sorbent. Elution was performed with potassium chloride. DNA-ligase T4 was eluted with 0.25-0.5 M KCl and RNA-ligase T4 with 0.08-0.18 M KCl. Since deoxyexonuclease contaminants possess stronger bonds with the sorbent than ligases, elution of deoxyexonucleases occurs at higher concentrations of KCl. Chromatography of enzymes on cibacron blue F3GA-CL-Sepharose 6B allows one to obtain DNA- and RNA-ligases essentially free of DNase and RNase contaminants.