[en] Unruh's technique of replacing collapse by boundary conditions on the past horizon (the xi-quantisation scheme) for the derivation of the well-known Hawking radiation is extended to the Kerr black hole for the scalar and especially for the spin half field. The expectation value of the energy momentum tensor is evaluated asymptotically in the xi-vacuum state yielding explicitly the net Hawking flux of scalar and spin half quanta. The appropriate statistical distribution that emerges naturally for Dirac quanta validates the xi-scheme for fermions and confirms the association of temperature with a Kerr black hole. (author)