Cancer pain occurs in about 30% of patients at diagnosis but increases in prevalence with advanced disease. Recent surveys suggest that over 80% of patients with advanced cancer have pain and about half of these patients experience pain that is inadequately controlled. This suggests that despite the 80% efficacy of standardized management approaches to cancer pain, patients with severe pain are likely to be encountered often in clinical practice. This is often the result of a combination of factors including inadequate pain assessment, under-dosing of medication, failure to educate and monitor patients and their carers, as well as a failure of medication to relieve pain. Assessment of a patient with cancer who is in pain should not differ from the assessment of any other patient with pain. Pain in a cancer patient may not be caused by cancer and opioids may be inappropriate. Treatment of cancer-related pain relies on a stepwise approach using non-opioid and opioid analgesics. Doses need to be titrated against analgesic effect and the presence of any adverse effects. Patients with cancer are often frail, elderly, and have some renal or hepatic impairment. They can be prone to the adverse effects of medicines. Neuropathic pain usually requires a combination of standard analgesic medicines and co-analgesic drugs and there is good evidence that this can result in good pain control. Patients with breakthrough (or episodic) pain are particularly challenging to treat and require additional approaches, such as radiotherapy, surgery or bisphosphonates.