Aim. To substantiate the optimal composition of the base of the semisolid dosage form with the thick extract of feverfew (Tanacetum parthebased on structural-mechanical, textural, adhesive and microscopic studies. Materials and methods. The study objects were samples of a semisolid dosage form with the thick extract of feverfew with various gelling agents and the reference drug “Irikar”. In the course of the research, a complex of structural-mechanical methods and the microscopic analysis of the samples were used. Results and discussion. The studies of structural-mechanical properties have determined the regularities in the rheological characteristics of the experimental samples made using different gelling agents. It has been found that the rheogram of the emulgel sample has a smooth transition from the elastic deformation region to the elastic-plastic one, which may indicate a more homogeneous distribution of the sample components. It has been also determined that the sample corresponds in the textural properties to the refenium) rence drug – “Irikar” cream. The structural-mechanical studies have substantiated the rational content of the gelling agent in the emulgel composition – 3 %. The results of rheological studies have been confirmed by the data of the microscopic studies. Conclusions. The data obtained are the basis for further pharmaceutical development of a drug with the thick extract of Tanacetum parthenium for the treatment of diseases of the musculoskeletal system.