Global left ventricular (LV) diastolic function has been reported to be disturbed under conditions of right ventricular pressure overload (RVPO). However, from the standpoint of regional wall motion, only a little information related to the mechanism of LV diastolic dysfunction is available. Eight patients with RVPO and 7 healthy volunteers were investigated using tagged cine magnetic resonance imaging. Regional diastolic fraction (RDF) was determined in 4 segments (anterior, lateral, inferior, and septal) in the mid-ventricular short axis section and in 2 segments (septal and lateral) in the 4-chamber section. A heterogeneity index was obtained from the RDFs of the short axis section. In the RVPO group, in both short axis and 4-chamber sections, the RDF of the septal segment was depressed, and it showed an inverse correlation with the right-to-left ventricular systolic pressure (RV/LV) ratio (r = -0.74, p < 0.05) in the short axis section. In the 4-chamber section, the RDF was lower in the septal segment than in the lateral segment (p < 0.05). The heterogeneity index in the RVPO group was greater than that in the control group (p < 0.01). The index correlated positively with the RV/LV ratio (r = 0.77, p < 0.05). The altered regional diastolic motion results in increased heterogeneity in regional diastolic motion.