The article considers establishing of the commercial business in the cities of Baikal Siberia. The author examines formation of the trade relations in the region and involvement of the local economy in the trans-regional market relations. The author analyzes main forms of the commercial business like retail delivery trade, fair trade, stationary trade. It is proved that at the relevant time fair trade prevailed over. Baikal Siberia fairs formed a complex chain which, on the one hand, formed a mechanism of market saturation with goods, demanded by consumers, and exporting of local products to the other areas, on the other hand, it related with a nationwide market and distributed the goods to the northern territories, to the Far East and the neighboring Asian countries. The author revealed that fair mechanisms were gradually replaced by more progressive elements of the stationary trade and Irkutsk was the main center of good distribution in the whole Siberian trade. The commercial business development influenced formation of the trade infrastructure in the Siberian cities with business districts, indoor market, and market places as trade centers.