Cancer patients are increasingly using CAM throughout the world. This has led to particular concerns among cancer health professionals with regard to the safe use of CAM with conventional medicine. In response oncology pharmacists need to be able to discuss CAM use with patients, and identify potential interactions with conventional cancer therapies, as well as adverse effects or contraindications. Patients invariably do not realize that drug–herb interactions may occur as the public often regard CAM as ‘natural and not harmful’. If there is evidence that CAM can be detrimental to health then it is important for this information to be imparted to patients and to colleagues involved in the care of cancer patients.