In the new conditions, it is necessary to rethink the concepts and models of various subsystems of the national economy’s activity, including small and medium-sized businesses, which makes study of the experience of the Islamic Republic of Iran as a resource country facing a high level of economic sanctions relevant. The aim of the article is to identify the features of the small and medium-sized enterprises’ activities of the Islamic Republic of Iran. The authors use methods of economic analysis, system-structural approach. The article establishes that the criterion for the classification of small and medium-sized enterprises is only the number of employees. Due to high inflation, the criteria of revenue and assets are not applied, industry affiliation is not taken into account. A significant proportion of small and medium-sized enterprises develop by replacing inaccessible goods and technologies, which leads to them having certain features. Firstly, small and medium-sized enterprises provide up to a third of the GDP of the Islamic Republic of Iran. At the same time, the falling behind of small and medium-sized enterprises in labor productivity is lower than in countries with mature market economies. Under the sanctions, a significant part of small and medium-sized enterprises of the Islamic Republic of Iran produce alternative imported products with high added value within the framework of small-scale production. However, the export potential of these products is limited. The specific ways of supporting small and medium-sized enterprises include the focus on the value chains creation (rather than the establishment of new enterprises) and the development of subcontract relations.