The adenine/cytosine1166 (A/C1166) polymorphism of the angiotensin-II type 1 receptor (AGTR1) gene is presumed to be associated with mitral valve prolapse syndrome (MVPS) in Caucasians. To investigate whether a similar association exists among the Chinese population in Taiwan, 100 patients with MVP diagnosed by echocardiography and 100 normal subjects were studied by polymerase chain reaction-based restriction analysis. The difference in genotype (chi2=0.24; p=0.89) and allelic (Yates' chi2=0.06; p=0.81) frequencies between the groups were not significant. Further categorization of the MVP patients into mild and severe subgroups also revealed no statistical difference from the controls. It was concluded that A/C1166 polymorphism of the AGTR1 gene is not a suitable genetic marker of MVPS in Taiwan Chinese.