(From Introduction) This paper aims to explore the conceptual motivation of the most frequently used English idioms related especially to the heart and other inside organs (collected on the basis of the Collins Cobuild English Dictionary [1995]), and their Hungarian equivalents (collected from bilingual general and idiom dictionaries). The aim of the research is to examine the similarities and the differences in the metaphorical and metonymical conceptualization of body parts including the heart and the inside of the human body in general, in English and Hungarian, which can lead to differences in the idiomatic language. The detailed analysis is also important with respect to the embodiment hypothesis as well as the general tendencies of universality and variation. It is argued that English body parts idioms can be analyzed together according to the specific body part areas they belong to, since body parts in the same areas usually share several target domains. According to the analysis of idiom database, body parts in the inside of the human body include the heart, blood, nerves, bones, flesh, and muscles. The heart in English is most frequently associated with emotions as it is seen as the seat of emotions due to the metaphor EMOTIONS ARE IN THE HEART. Frequently, the heart is seen as a container, or more generally, a fragile structured object, in which the emotions contained are substances, specifically fluids, because of the metaphors THE HEART IS A CONTAINER and EMOTION IS A SUBSTANCE (FLUID) IN A CONTAINER. Generally speaking, the inside organs can stand for the whole, i.e., the person, and thus can be used for purposes of personification. Also, they can be used to conceptualize various aspects of human attitude, characteristics, and actions. In general, the tendencies and the specific conceptual metaphors used in the Hungarian equivalents are similar to English. There are two major differences between English and Hungarian. Firstly, the literal meaning of the Hungarian equivalents differs from that of the English idioms. Often, Hungarian equivalents do not even use body parts in the expressions. Secondly, the soul plays just as important a role in Hungarian as the heart. In this way, the soul is seen both as the seat for emotions, and as a container. Thus, heart and soul in Hungarian can be used as source domains for the same targets. The systematic comparison shows that most often similarity between idioms and their equivalents exists on a generic level (the figurative meanings), and differences are on a specific level (the literal meanings, and the specific cognitive mechanisms), or result from cultural priorities. (Szilvia Csábi)