Left ventricular (LV) filling was examined by Doppler and M-mode echocardiography in 24 patients with LV hypertrophy (five with aortic stenosis, six with hypertrophic cardiomyopathy, and 13 with LV hypertrophy secondary to systemic hypertension) and in 18 normal subjects. Patients with LV hypertrophy had significantly lower Doppler-determined peak filling rates (218 +/- 17 vs 288 +/- 66 cc/sec, p less than 0.01), but M-mode determined peak rate of chamber enlargement and normalized peak rate of chamber enlargement did not differ significantly between groups. Doppler measures of the ratio between early and late filling were significantly depressed in patients with LV hypertrophy and correlated inversely with age in the normal subjects. The M-mode derived normalized peak rate of chamber enlargement and the Doppler-derived normalized peak filling rate correlated weakly, but significantly, when both groups were combined (r = 0.56, p less than 0.01). Thus Doppler measurements can detect abnormalities of LV filling in patients with LV hypertrophy. These abnormalities are present when M-mode filling indices and systolic function are still normal.