The article analyses Swedish and Finnish patent agents and their businesses at the turn of the twentieth century. Due to legal requirements, all foreign patent applications had to pass through the hands of patent agents. Despite the central role, this transnational business of technology intermediation has received only limited attention in the scholarship. The article studies the business relationships between the patent agents and their clients, and employs new datasets, which include information about all foreign patentees using a patent agent in 1860–1910. The main findings are that the transnational business relationships affected the specialisation of national patent agents, especially in Finland, where patent agents with a legal background contributed to the inflow of inventions managed by Swedish patent agents. Patent agent services also represented significant indirect costs of the patent systems for their foreign clients.