OBJECTIVES: The generic Short Form (SF)-36 is one of the most commonly used health status instruments in patients with cerebrovascular disease. However, a responsiveness to change - a pre-requisite for evaluative purposes - has not yet been assessed for neither the SF-36 nor its shortened version, the SF-12. Responsiveness to change describes the ability of health status instruments to detect clinically meaningful changes in HRQoL (health-related quality of life) over time. The main objective of the present study was, therefore, to determine responsiveness to change of the SF-12 questionnaire in patients with stroke and TIA. METHODS: Patients with stroke/TIA were included at admission to one of the four participating hospitals. HRQoL was assessed with the Physical (PCS-12) and Mental (MCS-12) Component Summary scales at baseline and after 12 months. Responsiveness to change was determined with the standardized response mean (SRM) and classified as small (SRM 0.20-0.49), moderate (0.50-0.79) or large (? 0.80). SRMs were calculated separately for patients after stroke and TIA, and according to stroke severity as measured with the NIH (National Institutes of Health) stroke scale. RESULTS: A total of 558 patients was included (55 % men, mean (standard deviation) age 65 (13) years; 45 % women, 69 (14) years). Indications for admission were stroke (74 %) and TIA (26 %). In patients with stroke, SRMs were moderate for both the PCS-12 (SRM 0.5; absolute change -5.9 (12)) and the MCS-12 (SRM 0.5; -6.6 (13)). In patients with TIA, SRMs were below 0.2 for the PCS-12 (absolute change -0.7 (11)) and 0.3 for the MCS-12 (-3.7 (11)). SRMs increased with stroke severity as indicated by the NIH stroke scale score. CONCLUSIONS: The SF-12 summary scales show a moderate responsiveness to change in patients after stroke. Responsiveness to change was higher in patients with increased stroke severity.