A prognostic system for transient ischemia or minor stroke. OBJECTIVE: To build a prognostic system for patients with carotid transient ischemic attack or minor stroke. DESIGN: Inception cohort study with 2-year follow-up. SETTING: Urban community teaching hospital. PATIENTS: Eligible patients (n = 142), identified on a carotid ultrasound roster, had been hospitalized between 1984 and 1987 within 30 days of a first carotid transient ischemic attack or minor stroke. MEASUREMENTS: Stroke or death within 2 years. MAIN RESULTS: Three factors were associated with stroke or death: age of more than 65 years, diabetes, and hypertension. Based on regression coefficients, age of more than 65 years was assigned 3 points; diabetes, 3 points; and hypertension, 2 points. An initial prognostic system comprised risk groups 1 (0 points), 2 (1 to 5 points), and 3 (6 to 8 points). Outcome rates in the three groups were 2%, 31%, and 54% (P less than 0.0001), respectively. In an independent test sample, the corresponding outcome rates for the initial system were 12%, 21%, and 31% (P = 0.04). A final prognostic system, including two additional predictors (coronary heart disease [1 point] and the distinction between stroke and transient ischemic attack for the baseline event [2 points]), comprised risk groups 1 (0 to 2 points), 2 (3 to 6 points), and 3 (7 to 11 points). Corresponding outcome rates were 3%, 27%, and 48% (P less than 0.001) in the original cohort and 10%, 21%, and 59% (P less than 0.001) in the test cohort. CONCLUSION: For selected patients with carotid transient ischemia or minor stroke, five clinical features can be combined to stratify effectively the risk for a subsequent stroke or death. 