The relaxation of the segmental orientation and the chain extension in polycarbonate have been studied by infrared dichroism and heat shrinkage after a step strain deformation to a draw ratio of lambda = 1.75. This makes it possible to distinguish between local relaxation mechanisms (Rouse) and large-scale relaxation mechanisms of the molecular orientation. It was found that the average relaxation time for segmental orientation is shorter and more temperature dependent than the average relaxation time for the chain extension. The segmental orientation relaxes almost totally at 170 degrees C (T-g = 148 degrees C) before the chain extension even starts to relax.