BACKGROUND: Treatment for lexical retrieval impairment has been shown to yield positive outcomes in individuals with aphasia due to focal lesions, but there has been little research regarding the treatment of such impairments in individuals with progressive aphasia. AIMS: The purpose of this study was to examine the therapeutic effects of a semantic treatment for anomia in progressive aphasia relative to the outcome in an individual with stroke-induced aphasia. METHODS AND PROCEDURES: Two individuals with progressive aphasia and one with aphasia resulting from stroke participated in the study. Each participant presented with fluent, anomic aphasia; however, one of the patients with progressive aphasia demonstrated characteristics indicating a likely progression towards non-fluency. Each participant received a brief, intensive treatment intended to improve lexical retrieval in the context of generative naming for selected semantic categories. Treatment tasks included guided lexical retrieval prompted by the identification and elaboration of items within semantic subcategories, as well as other semantic tasks. Treatment outcomes were quantified using standard effects sizes as well as nonparametric tests comparing pre- versus post-treatment performance. OUTCOMES AND RESULTS: One of the individuals with progressive aphasia showed large treatment effects for lexical retrieval of items from targeted semantic categories. The other progressive aphasia patient showed very small effects overall for treated categories. The individual with the focal lesion due to stroke showed medium-sized effects for trained categories as well as significant improvement on a standardised measure of naming. CONCLUSIONS: Findings indicate that intensive, semantically based treatment for lexical retrieval can result in positive outcomes in individuals with progressive as well as stroke-induced aphasia. Examination of individual differences suggests that the status of semantic and episodic memory may provide predictive information regarding responsiveness to treatment.