Despite enormous efforts that have been made in the search for novel drugs and treatments, cancer continues to be a major public health problem. Moreover, the emergence of resistance to cancer chemotherapy often prevents complete remission. Researchers have thus turned to natural products mainly from plant origin to circumvent resistance. Pectin and pH- or heat-modified pectin have demonstrated chemopreventive and antitumoral activities against some aggressive and recurrent cancers. The focus of this review is to describe how pectin and modified pectin display these activities and what are the possible underlying mechanisms. The failure of conventional chemotherapy to reduce mortality as well as serious side effects make natural products, such as pectin-derived products, ideal candidates for exerting synergism in combination with conventional anticancer drugs. Despite enormous progress in oncology therapy during the last decade, especially regarding the development of "smart drugs," cancer still remains one of the leading causes of death. Hence, the development of new therapeutic strategies remains a high priority. Natural compounds represent an important source of new "leads" with potent chemotherapeutic or chemopreventive activity. Structure-activity relationship studies have led to the development of natural molecules or of semi-synthetic analogs with higher activity or lower toxicity. Two of the best examples currently used in cancer therapy are paclitaxel and etoposide. In this review, we will describe what is known about one particular class of complex plant polysaccharides, pectin, and its potential anti-cancer activities.