Medicinal polymer films with the antitumor antibiotic doxorubicin have been developed for the treatment of malignant neoplasms of mucous membranes. The optimum concentration of doxorubicin in the films is 0.14 mg/cm 2 , and the optimum base material is hydroxypropylmethylcellulose. The optimum conditions of doxorubicin determination by HPLC have been established, which stipulate the use of a reverse-phase sorbent column Nova-Pak C18 (150´3.9 mm), an isopropanol -acetate (3 : 7) buffer (pH = 4,5) as the mobile phase, and a photodiode matrix detector. The chromatographic process parameters and the characteristics of the chromatographic peak of doxorubicin have been determined. A linear dependence of the area under chromatographic peak on the drug content in a sample is valid in the interval from 0.01 to 0.6 mg. The proposed method of the quantitative determination of doxorubicin in the parent substance and ready-to-use medicinal films is characterized by high sensitivity, reproducibility, and accuracy. Using this method, the stability of the main quality parameters of the polymer films with doxorubicin is established for a 24-month storage (observation time) at 4 ± 2°C in a place protected from sunlight. It is established that the films with doxorubicin produce rather insignificant cytotoxic action on the healthy tissues of mucous membranes of the oral cavity in rabbits.An important task in the oncology and pharmacy is the creation of effective preparations for the treatment of malignant neoplasms in mucous membranes. Such tumors are treated using drugs belonging to various groups, in particular, by antitumor antibiotics. Doxorubicin is among the most frequently used drugs of this group [1]. Unfortunately, high toxicity of such compounds upon intravenous administration poses serious problems, limiting the possibility to achieve the maximum possible therapeutic effect. A decrease in the side effects of cytostatics offers a way to increase the efficacy of antitumor therapy. In addition to the search for new drugs, an important direction is the development of new immobilized medicinal forms for the targeted delivery of active components to the focus of disorder. One promising method in complex treatment of local malignant tumors is offered by the use of biodegradable medicinal polymer films, which provides deposition of the active agent in the zone of application and ensures accurate drug dosage, stability, and high therapeutic efficacy [2].In order to make possible the quantitative determination of antibiotic in such medicinal forms, it is necessary to de-velop a method of analysis characterized by high selectivity and sensitivity at a relative simplicity of the analytical procedure. According to the pharmacopoeial article for doxorubicin (VFS 41-1796-88), the drug content is determined using a microbiological method of diffusion into agar with a test culture of B. cereus var. mycoides 537 (spores), which is rather laborious, time-consuming, and insufficiently specific. A relatively simple procedure based on the spec...