In contrast to other economic calamities such as financial crises or war, the topic of nationalisation has received only little attention by economic and business historians. Drawing on Russian and Swedish archival sources, this paper takes stock of the economic losses incurred on foreign investors in the 1917 Russian revolution, with particular emphasis on the Swedish case. Constructing lower and upper bounds for the losses, the paper argues that depending on the chosen measure these were in the range from 380 to 1,140 million SEK in 1917. For a country that remained neutral throughout two world wars, the Russian revolution represents one of the largest (if not the largest) externally incurred losses on Swedish firms and households in modern history. These results suggest that the role of revolutions in international business history needs to be better understood.