This study examines price dynamics in roundwood exports from Russia to Finland, the largest international roundwood trade flow within Europe. The analysis covers six main timber assortments; sawlog and pulpwood dimensions of pine, spruce and birch. The study period, starting from the devaluation of the rouble in August 1998, was characterized by a drastic increase in the volumes of Russian roundwood imported into Finland, and a coinciding structural change in the timber assortment distribution of the Finnish roundwood imports. A basic hypothesis of economic theory, the law of one price, was tested by using quarterly time series and methods of cointegration analysis. According to the cointegration tests, the prices of Finnish and Russian spruce sawlogs have moved closely together. Furthermore, the changes in the prices of spruce sawlogs in the Finnish roundwood market are reflected in the Russian prices and not vice versa. Regarding other timber assortments, price co-movement and consequent market integration was not detected.