The effectiveness of targeted delivery of cisplatin conjugate with arabinogalactan to ascitic Ehrlich carcinoma in vivo using the target ligand, the AS42 aptamer, was studied in this work. Studies conducted on male ICR mice with ascitic Ehrlich carcinoma. Antitumor therapy was carried out with cisplatin and an arabinogalactan-platinum complex (AG-Pt) and an AG-Pt complex modified with aptamers to ascitic Ehrlich carcinoma cells. The toxicity of drugs was determined on the basis of biochemical parameters of blood in healthy mice after 5-fold administration. In our studies, cisplatin treatment of Ehrlich's ascitic carcinoma for 2 weeks led to the death of 6 out of 10 animals. The toxicity of the AG-Pt complex and the AG-Pt complex modified with the aptamer was not revealed. The number of tumor cells during therapy with cisplatin conjugates decreased by 10 times compared with the control. А new promising antitumor drug based on the standard drug cisplatin, which is more effective and less toxic, was presented in the work.