Fatigue craze initiation in bulk, amorphous polycarbonate (PC) is investigated by means of transmission electron microscopy. The results agree very well with small angle X-ray scattering measurements of the same set of samples, and confirm that void generation is the main characteristic of the initiation process. The evolution of the initial void-like structures or ’protocrazes’ with dimensions of approximately 50 nm into crazes with dimensions of several micrometres is presented in considerable detail. It is found that some similarities exist between crazes induced by cyclic fatigue at room temperature and crazes produced in monotonic loading at temperatures close to the glass transition. The similarties suggest that disentanglement of polymer chains plays an important role in the fatigue craze initiation process in bulk, amorphous PC near room temperature.