The digital photoelastic technique was used to obtain an experimental solution of the transient thermal stresses of two interacting semielliptic surface defects due to a step temperature change at the free surface. A series of computer programs were developed on the digital photoelastic system to extract the maximum transient thermal stress on the defect boundary. By using a statistical analysis package, the variation of the maximum transient thermal stresses and their locations were correlated with the time, temperature difference, and geometrical parameters of the defects.