Apparatus and method for stack access throttling for synchronous ray tracing. For example, one embodiment of an apparatus comprises: ray tracing acceleration hardware to manage active ray tracing stack allocations to ensure that a size of the active ray tracing stack allocations remains within a threshold; and an execution unit to execute a thread to explicitly request a new ray tracing stack allocation from the ray tracing acceleration hardware, the ray tracing acceleration hardware to permit the new ray tracing stack allocation if the size of the active ray tracing stack allocations will remain within the threshold after permitting the new ray tracing stack allocation.