The United States National Cancer Institute (NCI) supports complementary and alternative medicine (CAM) research which includes different methods and practices (such as nutrition therapies) and other medical systems (such as Chinese medicine). In recent years, NCI has spent around $120 million each year on various CAM-related research projects on cancer prevention, treatment, symptom/side effect management and epidemiology. The categories of CAM research involved include nutritional therapeutics, pharmacological and biological treatments, mind-body interventions, manipulative and body based methods, alternative medical systems, exercise therapies, spiritual therapies and energy therapies on a range of types of cancer. The NCI Office of Cancer Complementary and Alternative Medicine (OCCAM) supports various intramural and extramural cancer CAM research projects. Examples of these cancer CAM projects are presented and discussed. In addition, OCCAM also supports international research projects.