Most patients with advanced cancer develop diverse symptoms that can limit the efficacy of pain treatment and undermine their quality of life. The present study surveys symptom prevalence, etiology and severity in 593 cancer patients treated by a pain service. Non-opioid analgesics, opioids and adjuvants were administered following the WHO-guidelines for cancer pain relief. Other symptoms were systematically treated by appropriate adjuvant drugs. Pain and symptom severity was measured daily by patient self-assessment; the physicians of the pain service assessed symptom etiology and the severity of confusion, coma and gastrointestinal obstruction at each visit. The patients were treated for an average period of 51 days. Efficacy of pain treatment was good in 70%, satisfactory in 16% and inadequate in 14% of patients. The initial treatment caused a significant reduction in the average number of symptoms from four to three. Prevalence and severity of anorexia, impaired activity, confusion, mood changes, insomnia, constipation, dyspepsia, dyspnoea, coughing, dysphagia and urinary symptoms were significantly reduced, those of sedation, other neuropsychiatric symptoms and dry mouth were significantly increased and those of coma, vertigo, diarrhea, nausea, vomiting, intestinal obstruction, erythema, pruritus and sweating remained unchanged. The most frequent symptoms were impaired activity (74% of days), mood changes (22%), constipation (23%), nausea (23%) and dry mouth (20%). The highest severity scores were associated with impaired activity, sedation, coma, intestinal obstruction, dysphagia and urinary symptoms. Of all 23 symptoms, only constipation, erythema and dry mouth were assessed as being most frequently caused by the analgesic regimen. In conclusion, the high prevalence and severity of many symptoms in far advanced cancer can be reduced, if pain treatment is combined with systematic symptom control. Nevertheless, general, neuropsychiatric and gastrointestinal symptoms are experienced during a major part of treatment time and pain relief was inadequate in 14% of patients. Cancer pain management has to be embedded in a frame of palliative care, taking all the possibilities of symptom management into consideration.