Semantic activation due to priming, and the time course of its dissipation, were examined. Following a word presentation, the subject performed one of three tasks: synonym, antonym, or rhyme production. The first presentation of a word together with the task was the primer. The second presentation of the same word occurred after 0 to 4 intervening words. Effects of priming were looked for in the speed of the first response to the second presentation of the word. A production facilitation occurred when synonym production was primed by antonym production to the same word, the primed word immediately following the primer. Facilitation decreased with increasing number of interpolated tasks. No effect was found when antonym production was primed by synonym production to the same word. The results are discussed in terms of spreading-activation due to active use of the associative link between the concept and its antonyms.