This paper examines the semantic structure of antonyms on the basis of some examples taken from Romanian. Both grammatical and lexical antonyms are considered with a view toward grasping the correspondence and differences between the two classes. Representative examples illustrate the following conclusions: (1) the distinction between lexical and grammatical antonyms is only a formal one; (2) the grammatical mark (the negative prefix) does not always show the direction of the semantic negation; (3) the intermediate term is designated by the same semantic marks as those of the first and last term; and (4) the oppositions materialized in the antonymous series have a more abstract character than other oppositions. It is expected that further typological studies will discover whether this situation is typical of Romanian or whether it corresponds to the semantic structure of other languages as well. (Author/AM)