Since October, 2005 when intravenous thrombolysis with rt-PA (IV-rtPA) for hyperacute stroke was approved, acute stroke care system (ASCS) has been under remodeling in Japan. We conducted a nation-wide survey to reveal the status of 5,398 acute hospitals in 2006. In this study, we investigated the differences in ASCS by population density. The replies of the questionnaires in terms of ASCS were divided into three groups based on the population density; highest tertile (H), middle tertile (M) and lowest tertile (L) groups. The answers of hospitals attending stroke patients were compared among the three groups. 1,586 hospitals (29.4%) responded. The upper and lower tertile thresholds were 2,050 and 461 people/km2, respectively. 65% of H group, 75% of M group and 76% of L group attended acute stroke patients (p=0.0001). 47%, 43%, and 50% had direct telephone line with the emergency services, respectively (ns). The early admission rate, within 3 hours of onset, over 20% of all was seen in 23%, 23% and 26%, respectively (ns). Stroke expertise physicians were available on a 24/7 basis in 56%, 63% and 45%, respectively (p<0.0005). 20%, 17% and 9% had Stroke unit, respectively (p<0.001). 9.5%, 7.1% and 2.4% treated more than 10 stroke patients with IV-rtPA per year, respectively (p<0.0001). In conclusion, the acute stroke care system was unsatisfactory, especially in the lowest tertile group by population density, at present in Japan.