The effects of a representative combustor exit temperature profile on leakage flow film cooling effectiveness were experimentally documented. This was done in a stationary, linear blade row cascade with an axisymmetric blade platform of dolphin-nose-shape. Endwall adiabatic film cooling effectiveness distributions and near-endwall passage thermal fields are documented. Results from the case with a representative combustor exit temperature profile are compared to those with other combustor exit temperature profiles including a base case with a uniform temperature distribution. All cases were done in the same facility over a range of disk cavity leakage flow rates. This study quantifies the sensitivity of endwall film cooling due to coolant in the leakage flow and in the approach flow to the shape of the combustor exit temperature profile. The results indicate that leakage flow film cooling effectiveness is significantly lower with a well-mixed (uniform temperature) combustor exit temperature profile than in cases in which the combustor exit temperature distribution is strongly variable. That is, it is demonstrated that combustor cooling flow aids endwall protection considerably. It is also shown that leakage flow has only a mild influence over the endwall cooling that can be attributed to coolant in the approach flow.