This paper deals with ionising radiation effects (X or γ-rays) in ferroelectric materials for electronic non-volatile memories. After the recall of main observations, mechanisms are analysed and proposed to take into account the effects in PZT-based capacitors. Fatigue of the hysteresis cycle are studied and linked to irradiation effects. As for irradiation, fatigue shows a damping of hysteresis curves. We show that a connection exists between fatigue and irradiation. A mechanism is proposed based on domain wall motion and pinning.