This paper presents a disaggregated regression study of the cyclicality of the mark-up over costs in Belgian manufacturing industry. This is found to be low, reflecting a great reluctance on the part of price setters to adjust prices to uncertain market signals. This appears to be especially the case for exporters when compared with firms active on the domestic market. Exporters face greater uncertainty because their competitors are less well-known, and their market shares tend to be smaller, implying a higher variance of industry sales estimates.