Effect of grid-generated mainstream turbulence on the film effectiveness and heat transfer coefficient of a turbine blade model was investigated at a chord Reynolds number of 3 x 10(5). The blade model had three rows of film holes in the leading edge region and two rows each on the pressure and suction surfaces. CO2 and air, with density ratios (DRs) of about 1.5 and 1.0, respectively, were used as film injectants. Results indicate that an increase in mainstream turbulence causes an increase in Nusselt numbers and a decrease in film effectiveness, over most of the blade surface, for both density ratio injectants at all blowing ratios.