This study represents the third in a series designed to assess aphasic listeners' ability to comprehend syntax. It addressed the issue of whether the presence of additional surface structure markers would facilitate the comprehension of syntactic distinctions based on tense, word order, ad relativization. The results indicate that the additional markers did significantly improve comprehension of tense and word-order distinctions for those aphasic subjects who achieved relatively low scores on the stimulus sentences not containing the additional markers. Those subjects who had relatively high scores on the sentences without the additional markers also benefited from the extra markers, but this improvement failed to reach statistical significance. These results are discussed in relationship to the concept of knowledge-based processing.