The therapeutic efficiency of recombinant thymosin β4 (rTβ4) synthesized by us was studied in vivo on spontaneous CBRB mouse model that is adequate to human chronic dermatitis. Three applications of the drug during a week significantly alleviated symptoms of the disease in female mice, and in complex with subsequent antibacterial and antifungal therapy led to a pronounced and lasting (2 months) therapeutic effect. The results attest to a possibility of using rTβ4 in combination with the known treatment protocols for chronic inflammatory diseases of the skin.