Timofey Evseevich Evseev (Evsevyev) is a well-known Mari ethnographer-collector, local historian, folklorist, who made a significant contribution to preserve and study the Mari traditional culture in the first third of the twentieth century. The museum collections that he collected on the material and spiritual culture of the Mari are the most valuable source for studying the ethnography and history of the Mari Region.
 
 The purpose of the study is to analyze the collection of manuscripts by T.E. Evseev on Mari traditional embroidery, collected during collecting and field activities in the 1905–1930s.
 
 Materials and methods. The research uses the methods of archival documents and museum accounting documentation analysis, the historical-comparative, historical-typological and quantitative methods. The handwritten documents of T.E. Evseev have been preserved in the fund of the National Museum of the Republic of Mari El named after T. Evseev, giving the opportunity to recreate the history of completing the museum with samples of Mari traditional embroidery in the first third of the XX century.
 
 Study results. The article provides valuable information about the collecting and field work performed by Timofey Evseevich Evseev during his pedagogical and museum activities. The main stages in his ethnographic surveys of Mari villages in order to collect handwritten and tangible material on Mari traditional embroidery are identified. The role of domestic and foreign ethnologists and museum specialists in forming the ethnographic collections of the Mari Regional Museum on the topic of embroidery is noted. On the basis of preserved manuscripts, accounting and clerical documents of T.E. Evseev, the article presents a quantitative analysis of museum collections of the first third of the XX century; the types of collected samples of traditional embroidery among various ethnoterritorial groups of meadow Mari are characterized.
 
 Conclusions. Materials on Mari traditional embroidery presented in the handwritten heritage of T.E. Evseev are the most valuable source for studying the development of traditional embroidery among various ethnoterritorial groups of the Mari and can be used to create exposition and exhibition spaces, to prepare museum catalogues and to develop museum and educational programs on the history and ethnography of the Mari people.