To evaluate the influence of left ventricular (LV) aneurysm on non-infarcted ventricular wall, the shape of the left ventricular wall was assessed by thallium-201 single photon emission computed tomography (SPECT). From the morphology of the ventricular wall close to the apex, the rest images along the transaxis, horizontal long axis and vertical long axis were classified into 4 types: convergent, parallel, divergent and completely defective. LV aneurysm was detected by 2-dimensional echocardiography and/or contrast left ventriculography in 39 of 80 patients with previous myocardial infarction. Although convergence in the normal configuration of ventricular walls close to the apex, 4 of 39 patients with LV aneurysm showed this pattern. The divergent type was very specific (100%) and the most sensitive (56.4%) of the 4 for identifying LV aneurysm. Moreover, the parallel configuration indicated aneurysm in cases of inferoposterior infarction and all the completely defective cases exhibited this abnormality. Thus, thallium-201 SPECT is suitable for observing the morphology of the ventricular wall and can provide highly reliable information for detecting postinfarction ventricular aneurysm with a sensitivity of 89.7%, a specificity of 87.8% and a diagnostic accuracy of 88.8%.