In order to establish a normalizing method for left ventricular filling indexes, peak filling rate (PFR) and time to peak filling rate (TPFR), derived from resting radionuclide ventriculography using Fourier analysis with third-order harmonics, were analyzed in 45 normal subjects, 40 hypertensive patients, and 29 patients with hypertrophic cardiomyopathy. PFR was significantly negatively correlated with age (r = -0.62) and significantly positively correlated with peak ejection rate (PER) (r = 0.58) in normals. TPFR normalized for heart rate (N-TPFR) was correlated positively with age in normals (r = 0.60) and hypertensives (r = 0.49) but not in patients with hypertrophic cardiomyopathy. N-TPFR was not significantly correlated with systolic parameters. A significant relationship between PFR normalized to PER (PFR/PER) and age was observed in normals (r = -0.58) but not in patients with hypertension or hypertrophic cardiomyopathy. To cancel the ageing effect, individual data of PFR/PER and N-TPFR were expressed as a percentage of the predicted regression value in normal subjects (%PFR/PER and %N-TPFR, respectively). Per cent PFR/PER was significantly lower and %N-TPFR was significantly greater in patients with hypertension and hypertrophic cardiomyopathy compared to normals. When normal limits of these indexes were defined as %PFR/PER greater than 80% and %N-TPFR less than 120%, the sensitivity, specificity and diagnostic accuracy of differentiating normals from patients with hypertension or hypertrophic cardiomyopathy were 41 of 45 (91%), 44 of 68 (65%), and 85 of 113 (75%), respectively. These findings indicate that %PFR/PER and %N-TPFR might be more reasonably normalized parameters for describing diastolic filling and its abnormality.(ABSTRACT TRUNCATED AT 250 WORDS)