This review is concerned with the presence of naturally occurring oestrogens in food plants and processed foods. Particular emphasis is placed on isoflavones and coumestans, both of which are true plant oestrogens, and the resorcylic acid lactones, more correctly classified as fungal oestrogens. The metabolism and mode of action of these compounds is discussed and their biological potencies, determined in both in vivo and in vitro studies, described. Current methods of analysis are indicated and the levels of these oestrogens in food plants, processed foods and feedingstuffs are presented. Botanical, environmental or technological factors affecting the possible intake of plant and fungal oestrogens are mentioned and the hazard associated with such intake is compared with that originating from other dietary or medicinal hormonally active substances. Indications are given of the wide range of common food plants which have been reported to possess oestrogenic (uterotropic) activity, although it is emphasized that in general further work is necessary to substantiate these claims and to confirm the identities of the biologically active principles which have in some cases been proposed. In the concluding section suggestions are made for additional research considered important or necessary in this interesting area.