The purpose of this study was to clarify whether or not a change in the clinical characteristics of cardiac myxoma has occurred during the past 2 decades. The clinical records of 57 patients (22 men, 35 women; age, 52+/-14 years) with myxoma that had been surgically treated between May 1978 and July 1997 at the National Cardiovascular Center in Japan were reviewed. All myxomas were discovered by transthoracic echocardiography. They were divided into an early group (n=30) treated in the first decade (1978-1987) and a late group (n=27) treated in the second decade (1988-1997). The incidence of myxoma, patient characteristics, preoperative symptoms and echocardiographic features did not differ between the 2 groups. In contrast, the maximal dimensions of myxoma in the early group were significantly larger than those in the late group (6.3 +/-2.7 cm vs 4.3+/-1.3 cm, p=0.012). The weight of myxoma in the early group tended to be heavier than that in the late group (76+/-80 g vs 25+/-18 g, p=0.054). The incidence of patients with asymptomatic myxoma also tended to increase in the late group (7% vs 26%, p=0.07). Although there was no difference in the incidence of myxoma, smaller and asymptomatic myxomas were more frequent during the last decade, probably as a result of the development of cardiac imaging, particularly echocardiography.