To study the prevalence and factors associated with opioid use in pain, 480 consecutive patients with a chief complaint of pain were interviewed at 10 clinics in Zahedan. The data were analysed in relation to 18 possible associated factors. The prevalence of opioid use was 28.5% in patients presenting with pain. There was no significant relation between opioid use and chronic pain [>/= 6 months], but there was a relationship with the following 5 factors:previous opioid use by friends [72.9% versus 20.4% without friends using], occupation [58.5% private sector employees/self-employed versus 17.4% housewives], cigarette smoking [60.8% versus 21.8% not smoking], consultation for a psychological problem [38.3% versus 23.3% without], and death of a spouse [60.0% versus 26.1% without]