Abstract Transcortical aphasic patients were assessed on a repetition task comprised of both well-formed and deviant sentences. The patients faithfully repeated those sentences that were factually incorrect but grammatically well formed, and those sentences that were ungrammatical because of selection restriction violations. In contrast, presented with sentences featuring only minor syntactic violations (e.g., lack of number agreement), the patients spontaneously, and without awareness, resisted exact repetition; moreover, the resultant changes most often served to correct the syntactic deviations. Repetitions of sentences of this latter type also revealed a difference between the patients as a function of level of comprehension. The transcortical motor aphasic patient was influenced by semantic factors in his alterations of the minor syntactic violations, while the transcortical sensory aphasic was not. These findings are discussed in relation to the notion of autonomous syntactic processing. They are taken to suggest that syntactic facts such as number agreement are represented at a level in the processing chain that is distinct from that of semantic representation.