Accessibility improvement has been regarded as one of the main regional policy goals in the recent decades. As a result, many countries has undertaken complex transport infrastructure investment programmes worth billions of dollars. The best examples of such investment can be China or, in the European context, Spain and more recently Poland. There have been published many analyses focusing on output and employment effects of transport infrastructure investment projects. Yet, there hardly exist any studies that verify their potential influence on interregional trade flows. This paper fills the existing gap in the literature by assessing the impact of accessibility improvement on the volume and the value of interregional trade flows in Poland between 2005 and 2015. We find that there is no statistically significant relationship between travel time reduction and interregional trade. This may explain largely the surprising lack of positive relationship between accessibility improvement and regional GDP growth, reported in previous papers.