A study of blast effects inside an enclosure was performed for a 1-lb C4 charge placed at the center of a rectangular bunker. The prediction based on the Euler equations shows good agreement with the test data. Predictions calculated by the method of images were also obtained to help illustrate the internal shock reflection effects. The results show that the confined blast loading is more complex than the free field loading due to internal shock reflections and interactions. Focusing of multiple reflections is possible and may cause significant late time loadings.