Abstract: This paper proposes a new method for fast ray/axis-aligned bounding box overlap tests. This method tests the slope of a ray against an axis-aligned bounding box by projecting itself and the box onto the three planes orthogonal to the world-coordinate axes and performs the tests on them separately. The method is division-free, and successive calculations are independent of each other. No intersection distance is computed, but it can be added easily. Test results show the technique is up to 18% faster than any other method known to us and 14% faster on average for a wide variety of different test scenes and different processor architectures.