By means of the Maslach Burnout Inventory, we examined job burnout among randomly selected nurses working on psychiatric (55 nurses) and medical units (51 nurses) at 2 university hospitals in Isfahan during 2003. Psychiatric nurses experienced a greater degree of emotional exhaustion than the medical nurses (P < 0.05). Significant positive correlation was noted between age, years of experience and frequency of on-calls and emotional exhaustion for the psychiatric nurses. Frequency of on-calls was also significantly associated with a sense of non-accomplishment. Longer duration of service was accompanied by higher degree of emotional depersonalization for the medical nurses.