This paper focuses on the history of opium trade between Iran and China in the long nineteenth century. Based on extensive archival research in multiple languages and countries, the paper explains how an opium industry developed in Qajar Iran, how Chinese consumption expanded during this period, and how an international trade across the Indian Ocean took opium from various points of origin to the Chinese market. The paper also deals with the global politics and economics of opium trade with China in the nineteenth century. The presentation demonstrates (1) the fluctuations in the production and export of opium in and from Qajar Iran, (2) how Iranians prepared this export commodity for the Chinese market, and (3) the ways in which they worked with other international merchants to convey opium consignments to their ultimate destination. There were at least two different trade routes used during this time: One was overland through Central Asia while the other one was a maritime route that took opium consignments from the Persian Gulf to various islands of the China Seas. Both of these trade routes were long established and had their origins in the fabled Silk Road. This paper also shows how Iranian merchants, landowners, and government officials worked together to maintain high profit margins in this highly competitive international business. Making use of a variety of techniques, Qajar opium dealers were not only able to maintain their long-distance trade networks with China; they also outcompeted the British, the Ottoman, and the Japanese opium merchants who were also involved in the production of opium in different parts of Asia and in opium trade with China. Much has been written about the importance of opium in the expansion of capitalism and in supporting imperialism in the nineteenth century. In this context, it is often opium production in India that has been considered important for the economic development of the British Empire and its expansion in different parts of the world including Asia and Africa. This paper engages with the scholarly literature on imperialism, the history of capitalism, and the production of opium and its trade in the nineteenth century. The argument here is that the Persian opium trade with China must be a key part of any discussion on the history of recreational drug trade in the nineteenth century because it contributed much to the development of economic change in Iran and the broader Middle East.