The article gives a brief description of the trade in the town of Kyakhta, examines the conditions, causes of the emergence and growth of smuggling, reveals methods and specifics of fighting illegal import/export of goods through the Kyakhta customs in the pre-revolutionary period. The task of the Kyakhta Customs, established simultaneously with the trading post in 1727, was not only the collection of duties to replenishing the treasury, but also the fight against smuggling. As the turnover of the Kyakhta trade increased and various restrictions were imposed by both the Russian Empire and Qing China, the assortment and volume of smuggled goods and methods of their delivery changed. At the same time, customs service methods aimed at fighting smuggling were improved. Legislative and normative legal acts, record keeping and reporting documents of Fund 102 "Kyakhta Customs" of the State Archives of the Republic of Buryatia, materials of pre-revolutionary periodicals allowed identifying a diverse arsenal of ever more complicated methods and ways to counteract illegal import/export of goods - from erection of special structures and ambushes to introduction of round-the-clock border patrols and development of a system of fines and punishment for smugglers. However, despite the legislative restrictions and prohibitions established by the state and the efforts made by the Kyakhta customs officers, the problem of combating smuggling remained intractable.