abstract: The work gives a description of the physicochemical properties of vegetable and animal fats, taking into acount also their effect on human health. It is a review-type work, presenting a descritpion of values characterising the quality of fats and thair suitability for consumption: acid number AN, saponification value SV, peroxide number PN, anisidine value AV, and iodine value IV. Numerous examples fatty acid profiles of vegetable and animals fats are given, as well as a discussion of factors affecting their composition. A detailed presentation is provided concerning the components of the non-saponifiable phase: squalene, carotenoid and chlorophyll pigments, tocopherols, polyphenolic compounds and sterols, their antioxidant properties, contents in various kinds of fats, as well as the parameters that determine those contents. The work presents also the effect of consuming fats on human health, the positive and the negative. The presented literature review, concerning both vegetable oils and animal fats, permits the readers to form their own views and opinions on the very important food components that we all consume daily. The advantages and disadvantages of fats have been the object of great interest, especially in recent years. However, the information given within the scope of that discussion is frequently fragmentary, and often burdened with the basic flaw of being part of advertising campaigns. There is, therefore, a shortage of information that would not be based on research results presented in a selective manner, but which would represent comprehensive data based on the latest achievements of science. For this reason the primary objective of the authors of this work was to accumulate the most important knowledge on the problem as a whole. The problem of quality of animal and vegetable fats, and the latter in particular, consists in the great instability of most of the biologically active compounds included in their composition. Yet it is the role of those compounds that is of special importance in terms of the quality and health properties of the food that we consume. The authors tried to emphasise not only the energy-source role of fats, that being equally health-promoting and noxious (especially in recent years, when our food contains increasing levels of industry-processed products). Numerous studies, especially those describing correct diet, focus on the role of faty acid profiles of various fats. Therefore, the authors made an effort to emphasise that role of unsaturated faty acids and to make the presentation objective. That role is important, because those acids play an unquestionable prophylactic role in the prevention of many of the civilisation diseases of the last century.