Background: Complementation information is a type of lexical-syntactic information that determines which syntactic environments a verb can be inserted into. It includes information about the verb's predicate argument structure (PAS), the thematic role of each argument, and the verb's subcategorisation frames. Complementation information might be impaired in aphasia. Various procedures have been used in treatment studies aimed at improving the production of verbs or sentences (including the verb with its arguments); these have usually yielded an improvement in treated verbs, without generalisation to untreated verbs. Aims: In this study, we evaluated a structured treatment procedure, aimed at improving impaired PAS information, and examined whether it improved the production of verbs with their arguments in sentences. The research questions were these: (a) Will treatment improve the production of verbs with their arguments in sentences? (b) Will improvement generalise to untreated verbs? (c) Will improvement be maintained after the end of the treatment? and (d) Will improvement generalise to connected speech (in a task of telling a story in response to a series of pictures)? Methods & Procedures: Two chronic aphasic patients with impairment in PAS information participated in the study. Their complementation information, and specifically their PAS information, was assessed prior to treatment, immediately after treatment, and in follow-ups 6 weeks and 6 months after treatment. The treatment consisted of instruction and practice on the number of arguments different verbs select, and taught the participants a strategy they could use. The practice was organised hierarchically, with regard to the number of arguments a given verb requires and the amount of cueing given. Outcomes & Results: Following treatment, a significant improvement was found in the participants' ability to produce sentences with the correct number of arguments. This improvement was generalised to untreated verbs and to connected speech and maintained for (at least) 6 months after treatment. However, neither participant showed improvement in other language skills, or even in other types of complementation information (i.e., subcategorisation frames).Conclusions: The findings suggest that structured treatment focusing on PAS information can improve the use of this specific type of information, manifested in the production of sentences including the verb with its arguments. Theoretically, the findings support the view that complementation information is represented separately from other types of language information, and they suggest that different types of complementation information might be represented separately.