Population-based data on complementary and alternative medicine (CAM) use among cancer sufferers is lacking. In a telephone survey representative of California households (response rate = 68.9%, N = 1845) those who reported a diagnosis of cancer (excluding non-melanoma skin cancers) were asked about CAM use. CAM use is substantial, although with few exceptions, it is approximately that found among those with non-malignant chronic conditions. Those with cancer are more likely to report praying for their health, using support groups, and taking multiple dietary supplements. They are less apt to use CAM providers or special diets. Socio-demographic factors associated with CAM use vary by specific CAM modality. Site of the cancer was not associated with any particular CAM modality. The use of CAM therapies specifically promoted as cancer therapies was not common, especially among those diagnosed recently. The use of CAM providers and mind-body techniques specifically for the purpose of treating cancer is unusual (<10%), while special diets are more frequently employed for the purpose of treatment and/or prevention of the cancer itself. A clear majority of those who do use CAM for treating cancer report at least some benefit from the treatment, and are likely to inform their physicians of such use.