Twenty patients who suffered from RHD and CHF were randomly divided into the test group (n=12) and the control group (n = 8). Captopril was given orally before and after operation only in the test group. The results showed that the plasma level of ANF declined obviously in the test group. This may illustrate that the therapeutic effect of the captopril on the failing heart can be exerted by suppressing the secretion of ANF. The data also suggest that captopril might have some inhibitory effect on the reactions to the in-traoperative stress.