In this review of the experimental research on metaphor, the concept of metaphor is briefly described, and two main theories presented: the comparison theory (or similarity theory) and the interaction theory. According to the comparison theory, a comparison of features between the two concepts involved in the metaphor is the fundamental process underlying the interpretation of metaphor. According to the interaction theory, a metaphor induces the emergence of features that are associated neither with the topic nor with the vehicle of the metaphor. To gather evidence in favor of one or the other theory, two experiments were conducted using either macroscopic methods (e.g., sentence completion tasks, judgment tasks, and memory tasks) or microscopic methods (e.g., lexical decision tasks, reading time, and functional imaging techniques). A synthesis of main factors investigated (similarity, comprehensibility, context) is presented. It is concluded that neither theory was supported by the data analysis. (LLBA 2000, vol. 34, n. 3)