A highly effective cell-free system for protein synthesis was obtained from rabbit reticulocytes and for the first time used for synthesis of biologically active chicken interferon. The optimal conditions for translation of its mRNA were developed. The translation efficacy in the cell-free system was 10-50 times higher than that in the culture of heterologous cells. The higher the purity level of RNA, the higher the translation level. With respect to poly (A+) RNA sedimenting in the sucrose gradient 9S the efficacy reached 2560 units per 1 microgram of RNA. By the content of poly (A), sequences and rate of the sedimentation, mRNA of the chicken interferon was similar to that of the human fibroblast cell interferon. The possible translation of mRNA of the chicken interferon at low concentrations of exogenic potassium ions in the cell-free system is explained by production of interferon in infected cells where the concentration of the intracellular potassium significantly decreases which is indicative of the mRNA interferon similarity with virus templates. It was found that only albino New Zealand rabbits, but also chinchilla may be used for preparation of the cell-free protein synthesizing system. Various exogenic templates in the mRNA-dependent cell-free system prepared from reticulocyte nonfractionated lysate by treatment with micrococcal nuclease stimulated the protein synthesis by 7-15 times.