Objectives Cancer patients have a high incidence of concurrent chronic diseases, the pharmacological treatment of which is generally complex and carries an inherent risk of drug-related problems (DRPs). DRPs can interfere with the patient's health outcomes. No systematic investigation of the prevalence of DRPs in hospitalised cancer patients has been performed in Norway. The aim of this study was to characterise the DRPs on an oncology ward, using systematic medication review, and to suggest interventions to optimise drug therapy. Methods A clinical pharmacist applying the integrated medicines management method reviewed the drug treatment of 48 in-patients. The identified DRPs and the interventions proposed by the clinical pharmacist were discussed with the oncologists and oncology nurses, and the conclusions were characterised. Results 100 DRPs were identified through medication review. Of these, 41% were identified in the medication charts, 21% by evaluating the choice of drug and 21% by evaluating drug dosing. 75% of the suggested interventions for DRPs were implemented in the drug therapy of the patients.Conclusions The results of this study demonstrate that the suggested interventions for reducing DRPs were frequently implemented by oncologists. The results also demonstrate that a clinical pharmacist, using medication review on an oncology ward, probably can improve the quality of the drug treatment of hospitalised cancer patients. BACKGROUND