A flame ionization technique based on the heat/mass transfer analogy has been used in an experimental investigation of film cooling effectiveness. The measurements were made over the surface of a turbine blade model composed of a semi-cylindrical leading edge bonded to a flat after-body. The secondary flow was injected into the boundary layer through four rows of holes located at ± 15 and ± 44 deg about the stagnation line of the leading edge. These holes, of diameter d, had a 30 deg spanwise inclination and a 4d spanwise spacing. Adjacent rows of holes were staggered by 2d, and perfect geometry symmetry was maintained across the stagnation line. Discharge coefficients and flow division between the 15 and 44 deg rows of holes have also been measured. The strong pressure gradient near the leading edge produces a strongly nonuniform flow division between the first (± 15 deg) and the second (± 44 deg) row of holes at low overall mass flow ratios