Recently, pulsed Doppler echocardiography has been used for the quantitative evaluation of tricuspid regurgitation (TR). However, there are some problems about the clinical significance of TR diagnosed by Doppler examination probably because of the excellent sensitivity in detecting TR. In the present study, we used liver function tests as an indicator of the visceral damage caused by TR and compared them to the severity of TR estimated by Doppler examination. Forty Doppler examinations were performed in 33 cardiac patients including seven, in which the examinations were repeated because the severity of TR changed during the clinical course. The severity of TR was classified into four grades according to the maximal extent of the regurgitant signal. Abnormal liver function was defined by the abnormalities of at least one of the following six tests: cholinesterase (CHE), gamma-GTP, leucine aminopeptidase (LAP), total bilirubin, alkaline phosphatase and GPT. Abnormal liver function tests were present in one of eight patients without TR, two of 10 with 1 + TR, four of seven with 2 + TR, seven of eight with 3 + TR, and six of seven with 4 + TR. The incidence of abnormal liver function tests increased parallel to the grade of TR and was very frequent in patients with 3 + or 4 + TR. TR diagnosed as greater than 3 + by Doppler examination is considered to have an important clinical significance and an indication of the intensive therapy.