This article reports investigations into the behaviour of gross profit margins (mark-ups) in Turkish manufacturing industries for the post-1980 liberalization period in relation to price inflation, trade liberalization (openness) and real wage costs. Panel data econometrics over 29 subsectors of Turkish manufacturing are used over the period 1980-1996. Results suggest that profit margins are positively and significantly related both to price inflation and real wage costs. However, openness is found to have very little impact on profit margins. © 2005 Taylor & Francis.