Analogies are believed to help students structure new knowledge and are considered to be especially useful for topics of an abstract or submicroscopic nature. Analogies, however, have also been identified as a factor in the students' misunderstanding of chemical concepts. This paper reports on the literature identifying the advantages and constraints of the use of analogies in chemistry education. The term "analogy" is defined and three types of analogies--verbal, picture, and personal--are described. Analogies are used in three major ways: to provide visualization of abstract concepts, to compare similarities of the students' real world with the new concepts, and to provide a motivational function. The following constraints of analogies are described: analog unfamiliarity, stages of cognitive development, and incorrect transfer of attributes. An examination of analogies found in textbooks currently used by Australian high school students is discussed with respect to these identified advantages and constraints. Results of the content analysis revealed that only 4.3 percent of the books had specific warnings or limitations on the use of analogies. Only 21 percent of the analogies presented included any statement identifying the strategy such as "an analogy,""analog," or "analogous." This study concludes that textbook authors may be underestimating the difficulties that students encounter when attempting analogical transfer. (Contains 15 references.) (PR)