Various support techniques for surgical treatment of type B aortic dissection have been used and recommended in many medical centers. In the last 21 years, 55 patients with type B aortic dissection underwent 65 operations including 10 reoperations, and 10 cases showed Marfan's syndrome. As circulatory support during operation, venoarterial bypass mainly was used until March 1987 (period I) and low-dose heparinized left heart bypass was applied since April 1987 (period II). Surgical results were compared among subgroups by the Kaplan-Meier actuarial method and Cox-Mantel statistical analysis. After the operation, early mortality was 27.3% in 33 patients in period I and 9.4% in 32 patients in period II (p = 0.06). The incidence of fatal hemorrhagic complications was decreased significantly by using the left heart bypass technique (p < 0.02). The 5-year actuarial survival of type B dissection was 60.6% in period I and 79.2% in period II (p = 0.07). These results suggest that surgical results of type B aortic dissection in this series might be improved with the introduction of left heart bypass and extended surgical procedures.