Production of recombinant human apolipoprotein A-I (apoA-I) in E. coli cells is described and its biological properties are compared with those of natural protein. Recombinant apoA-I was isolated as a chimeric polypeptide and then processed to a mature form apoA-I (rapo-I). We studied the ability of the resulting protein to penetrate into hepatocyte nuclei and regulate the rate of DNA biosynthesis in complex with estriol. Penetration of rapoA-I conjugated with FITC into hepatocyte nuclei was demonstrated. rapoA-I-estriol and apoA-I-estriol complexes induced similar increase in DNA biosynthesis rate in isolated hepatocytes, which confi rms functional similarity of the obtained recombinant mature protein (rapoA-I) and native human apoA-I.