Recent advances have contributed to our understanding of how a plant-based diet confers many health advantages and how substances from plants may be effective in the prevention of specific cancers. The Ninth Annual Research Conference of the American Institute for Cancer Research has focused on the latest developments in several categories of nutrients of wide contemporary interests. The conference sessions included such topics as the effects of soy, green tea, selenium, wine, grapes, and spices in cancer prevention. This conference was held in Washington, D.C. on September 2nd and 3rd, 1999, and was entitled Nutrition and Cancer Prevention: New Insights Into the Roles of Phyhemicals. The discussion program included a session that was devoted to the current status of herbal products in relation to cancer prevention, in recognition of the increasing attention that complementary and alternative medicine has been receiving from the scientific community as well as the general public. A separate presentation addressed the issue of nutritional supplements and cancer prevention.