The aim of the study is to analyse the scholarly trips abroad made by Polish mathematicians, with particular focus on where they went, how their trips were financed, what contacts they made and what the effects of such contacts were. The study is based on the analysis of archival materials, published research and memoirs. The practice of going abroad to establish scholarly contacts was quite widespread among Polish mathematicians of the interwar period (1918-1939). They travelled all over Europe, but made trans-Atlantic trips as well, with most of the scholarly trips directed to those academic centres which excelled in mathematical topics that the scholar was engaged in. Professors made trips abroad in order to acquaint themselves with the latest research or on invitations to lecture on their own achievements. Junior scholars went abroad for scholarships of several months duration, in order to follow lectures given by, and to work with, the top mathematicians of the time. Both senior and junior mathematicians attended international mathematical conferences and congresses. During their trips abroad mathematicians had a chance to learn about the centres they visited and meet the scholars who worked there. They could also present their own work to their foreign colleagues. The contacts they established bore fruit not only in individual achievements, but also benefitted Polish mathematics as a whole. More and more foreign scholars started to visit Poland, including both junior researchers and renowned professors, who had a chance to see Polish universities and collaborate with Polish mathematicians, giving lectures and taking part in conferences.