This article discusses interjectional phraseological units in the Shughni language which is one of the non-written Eastern Iranian languages spoken in Afghan and Tajik Badakhshan - in the Amu Darya headwaters region. The number of its speakers is estimated to be approximately 100-150 thousand people. The research is based on more than 5 000 phraseological units newly collected by the author within the period of 5 years in the territory of the Gorno-Badakhshan Autonomous Region of Tajikistan. Shughni phraseology has been studied in a few general articles only and, thus, requires further analysis in terms of semantics and grammar. The paper presents the first linguistic analysis of the voluminous materials. In addition to such types of phraseological units as verbal, adverbial, substantival, modal, adjectival, copulative ones and others, the collected materials also contain interjectional phraseological units that constitute approximately 3 to 7 % of the total scope. Interjectional phraseological units are semantically characterized by frequent reinterpretation, increasing emotional/evaluative connotations, expressive semantics and their application in the form of modal units in different contexts. Interjectional phraseological phrases express emotions, declaration of will and have emotional/evaluative figurative meanings. The diverse expressed emotions - enthusiasm, indignation, approval, surprise, annoyance, resentment, distrust, delight, excitement - serve to denote censure, warning, greeting, invitation and vows. Set phrases are used in the Shughni language to convey the will of the speaker and for other more general objectives. Most of them are idiomatic and stem from different historical periods being usually used in different communicative contexts to reflect emotional reactions of communicants. In different speech situations they perform modal functions based on the emotional evaluation of events. Some of them require broader cultural and historical comments. Each phraseological unit has a unique semantic structure; in terms of grammar, rarely do those differ from modern Shughni. Each phraseological unit has its own history of formation and adaptation to the Shughni language environment and requires to be considered separately. Ancient phraseological units have been well preserved in the Shughni language, moreover, for most of the speakers those are not loan ones. There are also common-Persian and foreign-language phrases (mostly Arabisms with few Turkisms).