This paper provides estimates of mark-ups of product prices over marginal costs for 36 manufacturing industries in 14 OECD countries over the 1970- 1992 period. The estimates are based on the methodology put forward by Roeger (1995), extended to include intermediate inputs. After a discussion of analytical and data issues, the estimates are presented and shown to be smaller than those of previous studies. It is also shown that the level and dispersion of mark-ups are consistent with a priori views about characteristics of the market structure prevailing in each industry. Finally, the paper examines how mark-up estimates affect the estimated rate of growth of total factor productivity (TFP) ...