Quantification of the regurgitation amount is important before and after valvular replacement surgery. Until now cardiac catheterization with cineventriculography, echocardiography have been used to measure the regurgitation amount, but also have many limitations. EKG gated cardiac blood pool scan provides a simple, non-invasive -method for quantify the regurgitation amount. By calculating the ratio of left ventricular to right ventricular stroke counts (stroke volume ratio) in gated bood pool scan, we measured the left ventricular regurgitation amount in 28 cases of valvular regurgitation and 25 cases of normal group. 1. Stroke volume ratio was higher in cases of valvular regurgitation $(2.11{pm}0.58)$ than in cases of normal control $(1.15{pm}0.31)$. (p<0.01). 2. Stroke volume ratio was classified by regurgitation grade using X-ray cineventriculography. In grades of mild regurgitation $(Grade;I{sim}II)$, stroke volume ratio was $2.02{pm}0.29$, and in grades of severe regurgitation $(Grade;III{sim}IV)$, stroke volume ratio was $2.55{pm}0.34$, so stroke volume ratio was well correlated with the grade of X-ray cineventriculography. 3. Stroke volume ratio was classfied by functional class made in New York Heart Association. In classes of mild regurgitation $(class;I{sim}II)$, stroke volume ratio was $2.08{pm}0.26$, and in classes of severe regurgitation $(class;III{sim}IV)$, stroke volume ratio was $2.55{pm}0.38$, Stroke volume ratio well represented the functional class. 4. After aortic and mitral valve replacement in 28 patients, the stroke volume ratio, decreased from $2.11{pm}0.58;to;1.06{pm}0.26$. Gated blood pool scan provides a noninvasive method of qnantifying valvular regurgitation and assessing the result of surgical interventions.