Our purpose was to determine the pain experienced by patients during root canal treatment and to correlate with age and gender, pulpal diagnosis, previous periapical status, dental characteristics and length of treatment. One hundred and seventy-six patients (68 men and 108 women), with ages ranged from 6 to 83 years, were randomly recruited. Patients completed a 10-cm visual analogue scale (VAS) that ranked the level of pain experienced during root canal treatment. The mean pain level during root canal treatment was 1.2 ± 0.8 in a VAS between 0 and 10. Fifty-four per cent of patients did not experience pain. There were no significant differences in relation to gender or age groups. Mandibular teeth had a significantly (P