[en] Fourteen patients with chronic renal failure (CRF) were studied by dipyridamole ²⁰¹Tl myocardial scintigraphy. In this study, patients with coronary heart disease were excluded by clinical findings. ²⁰¹Tl SPECT was performed at 8 min after injection of dipyridamole (0.56 mg/kg) and at a 3-hr delayed interval, and washout rates (WR) were calculated. Because UCG showed left ventricular hypertrophy (thickness; 13±2 mm) in CRF, the WR values were compared with those of hypertrophic cardiomyopathy (HCM)(n=9). In CRF, an average WR was 54.2±6.8% and was significantly higher than that in normal (46.2±9.1%, p<0.05, n=9), though WR in HCM was significantly low (26.9±11.4%, p<0.01). Hematocrit value was 24.5±3.2% in CRF and was significantly lower than that in normal (37.8±3.6%, p<0.001). On the other hand, hemoconcentration was observed in HCM (hematocrit; 44.6±3.6%, p<0.001). WR in CRF, HCM and normal had significant correlation with hematocrit values (r=-0.796, p<0.001). These results suggest that anemia or hemoconcentration may affect coronary blood flow and WR, and this should be considered when diagnosing coronary heart disease in CRF or HCM. (author)