Many people with cancer experience pain, anxiety, and mood disturbance. Conventional treatments do not always satisfactorily relieve these symptoms, and some patients may not be able to tolerate their side effects. Complementary therapies such as acupuncture, mind-body techniques, massage, and other methods can help relieve symptoms and improve physical and mental well-being. Self-hypnosis and relaxation techniques help reduce procedural pain. Acupuncture is well documented to relieve chronic cancer pain. Massage and meditation improve anxiety and other symptoms of distress. Many dietary supplements contain biologically active constituents with effects on mood. However, not all complementary therapies are appropriate or useful, and even helpful complementary modalities may not be optimal under some circumstances. Situations when precaution is indicated include acute onset of symptoms and severe symptoms, which require immediate mainstream intervention. Dietary supplements are associated with serious negative consequences under some circumstances. The authors summarize the research on these modalities and discuss the rationale, expectation, and necessary precautions involved with combining complementary therapies and mainstream care. Practical clinical issues are addressed.