OBJECTIVE: To assess chronic aphasic patients' responses to resumption of therapy using an innovative, computer-based treatment system. DESIGN: Patients were assessed pretreatment and posttreatment using standardized assessment tools. Pretreatment and posttreatment performance score means were computed and compared, with statistical significance of the differences established using a one-tailed, matched t test. SETTING: The work was conducted at (1) a Veterans Affairs medical center participating in treatment research and (2) a regional aphasia center delivering therapy services for reimbursement. PATIENTS: Chronic aphasic patients (n = 23) from 6 months to more than 15 years postonset were enrolled in the study. They included a wide range of types and severities of aphasia, and all had received traditional speech-language therapy services earlier. INTERVENTIONS: All patients were treated in 1-hour clinical sessions by speech-language pathologists using the designated computer-based treatment system. All but one of the patients had access to the computer-based treatment system at home for practice between clinical therapy sessions. MAIN OUTCOME MEASURES: The outcome measures used were (1) the Porch Index of Communicative Ability (PICA), (2) the Boston Naming Test (BNT), (3) the Western Aphasia Battery (WAB), and (4) the Boston Diagnostic Aphasia Examination (BDAE). RESULTS: The majority of patients improved significantly in multiple modalities as assessed by these instruments. CONCLUSIONS: Specific measures of language function can be broadly, positively, and significantly influenced by computer-based language therapy in chronic aphasia.