Constipation is common (40-90%) in advanced cancer patients , and has a significant negative impact on quality of life. The aetiology of constipation is often multifactorial in advanced cancer patients. However, it is well recognised that opioid analgesics are a common cause of constipation in this group. The prevalence of opioid-induced constipation (OIC) is stated to be 40-70%, although a recent large study reported an even higher figure. OIC has been reported to exceed pain in terms of distress caused, and studies have found that some patients choose to reduce or discontinue opioid medication in order to attempt to better control constipation. Moreover, OIC is associated with a variety of physical (gastrointestinal, systemic), psychological and social problems.