The research examined relational processing following stroke. Stroke patients (14 with frontal, 30 with non-frontal lesions) and 41 matched controls completed four relational processing tasks: sentence comprehension, Latin square matrix completion, modified Dimensional Change Card Sorting, and n-back. Each task included items at two or three levels of relational complexity. Relational processing was impaired in the stroke groups. This was due mainly to items at the intermediate ternary-relational level of complexity. Less complex binary-relational items and more complex quaternary-relational items (the latter are difficult for adults generally) were less sensitive to stroke status. Impairment was greater in frontal than non-frontal stroke patients. Positive inter-correlations among measures supported the domain-general nature of relational processing. Implications for assessment and intervention are discussed. (Contains 5 tables.)