The Krasnoufim Mari is a group of Ural Mari people, whose traditional clothing was marked by bright originality. They attracted the attention of travelers, researchers, local historians, ethnographers, art historians. The costume of the Ural Mari was repeatedly described by researchers of the 18th-19th centuries, and in the 20th-21st centuries it was the object of study of both Russian and Finnish ethnographers of different generations. The earliest evidences about the costume of the Ural Mari left by P.S. Pallas. In the 19th century the clothing of Mari people of Krasnoufimsky uyezd was described by G. Gorodskoy (V.N. Shishonko), S. Som-mier, D.P. Nikolsky. In the twentieth century the costume of this group of Mari ethnos was studied by T.E. Evseviev, S.N. Shitova, T.L. Molotova, as well as by A.O. Heikel and I. Lehtinen. In the 20th centure only one article devoted to the clothing of the Krasnoufim Mari people was published, and in the 21st century a number of richly illustrated articles and editions were published, the chapters of which were devoted to the costume of the Ural Mari people. Some of them are based on the materials collected in the Krasnoufim District of the Sverdlovsk Region. Three main bodies of sources on the topic were grouped by the researchers of the 18th-21st centuries: texts; collections of clothing items; photo-documents. In this article the history of formation of all three groups of sources is considered, as they were interrelated and represented often only different parts of a single research process.