This article discusses Swiss counterintelligence measures against Chinese espionage during the Cold War, focusing on the problems the Swiss Federal Police encountered when trying to uncover and eliminate the national and transnational intelligence networks the PRC operated from Switzerland in the 1950s and 1960s. Using newly declassified Swiss Federal Police files, the article details the Swiss federal counterintelligence system as well as the Federal Police filing system, showing the effects this had on the surveillance and investigation of Chinese officials and their contacts in Switzerland and abroad. It also describes Swiss Federal Police methods for identifying intelligence agents among the Chinese diplomatic staff, as well as the problems encountered with wiretapping and surveillance by car. Finally, the article details the Federal Police's cooperation with other countries in investigating China's international espionage networks and trade in embargoed goods.