AbstractThis work analyses the firms' internationalisation strategies of importing intermediates and exporting output, and the potential rewards of these activities in terms of total factor productivity (TFP), as a proxy for marginal costs, and markups. It further deepens into the study of the relationship between internationalisation strategies and markups by disentangling whether it operates through affecting firms' marginal costs and/or firms' prices. The panel database employed in this paper is the Spanish Survey on Business Strategies (ESEE) for the period 2006–14. Results in the paper distinguish between SMEs and large firms and indicate that there is high persistence in the performance of these activities and in firms' TFP and markups. For SMEs, we obtain rewards from importing inputs as well as exporting output in terms of TFP and markups. For large firms, we obtain rewards in TFP from the importing activity and rewards in markups from the exporting activity. Finally, we find evidence that the effects of internationalisation strategies on markups are due to both a price channel and a marginal cost channel.