In 1986 the World Health Organization (WHO) released guidelines for cancer pain relief. Since then, several controlled studies on effectiveness and practicability of these guidelines have been published. Various authors described inadequate use of these guidelines. We analysed, whether the pain medication of 160 cancer patients referred to the anesthesiological pain clinic at the university hospital of Vienna corresponded to the WHO guidelines or not. Adequacy of pain treatment was assessed using the pain management index (PMI). Multiple criteria were chosen to assess the conformity of the treatment with the guidelines. Furthermore we studied the effect of a strict use of the WHO guidelines in these patients. The average pain intensity of the referred patients was 75 mm (VAS). Negative PMI scores, indicating inadequate pain therapy, were found in 39 % of cases. A violation of the rules was found in 38% of the therapy schedules. Pain medication was then modified by switching to fixed time intervals, escalation of the steps of the WHO ladder, increasing the dosage or treating neuropathic pain with adjuvant drugs. Two weeks later the average pain score of the patients was reduced to 27 mm (VAS). At that time 72% of the patients quoted an adequate reduction of pain. Inadequate knowledge or disregard of the WHO guidelines for cancer pain relief are common and result in unnecessary and prolonged suffering in these patients.