Retrospective analyses of the stress thallium studies of 51 patients with a history of previous infarctions or definite stable angina were performed in order to determine the extent of the coronary-artery disease (CAD). The results were correlated with recent coronary-angiography findings in order to assess the effect of including right-ventricule (RV) visualization on the accuracy of the detection of right coronary-artery (RCA) disease, as well as the effect of graded stenosis or occlusion of the RCA and the presence of disease of the other coronary vessels on the visualization of the RV. Eight patients had normal coronary arteries. The other 43 patients had CAD, only 5 of whom had single-vessel RCA disease. With regard to the RV, 6 patients had nonvisualization, 30 had patchy visualization, and 15 had normal visualization in the stress thallium studies. Nonvisualization indicated 100% occlusion of RCA in 6 out of 6 patients. Patchy visualization indicated significant occlusion of the RCA in 25 out of 30 patients (83%), while normal visualization indicated a normal RCA in 13 out of 15 patients(86%). Normal visualization did not mean that the possibility of RCA disease could be excluded. When RV visualization data were added to LV images, the sensitivity for detecting RCA increased from 66% to 94% (P less than 0.05), the specificity decreased from 89% to 72% (P less than 0.1), and the predictive accuracy increased from 75% to 86% (P greater than 0.1).