Clinicians often have a difficulty in determining the presence of mitral regurgitation (MR)-related symptoms because of subjectivity. However, there are few actual measurement data for echocardiographic left ventricular (LV) and left atrial (LA) size related to the severity of MR and the relationship between MR-related symptoms and these echocardiographic parameters. Among patients enrolled in the Asian Valve Registry, we investigated 778 consecutive patients with primary MR showing sinus rhythm. Symptoms were determined by New York Heart Association grade (≤ II or ≥ III). MR severity was mild in 106, moderate in 285, and severe in 387 patients. LA volume index, LV end-diastolic diameter, and LV mass index increased with increasing MR grade [LA volume index: 47.9 (mild), 56.2 (moderate), and 64.9 ml/m² (severe) (p < 0.001), LV end-diastolic diameter: 51.2, 54.5, 58.1 mm (p < 0.001), and LV mass index: 101, 109, 123 g/m² (p < 0.001)]. Regarding moderate and severe MR, 70 patients (10.4%) were symptomatic. In multivariable analysis, for being symptomatic in moderate and severe MR patients, LV mass index (odds ratio [OR] per 10 g/m² increment; 1.09; 95% confidence interval [CI]: 1.005–1.18, p = 0.040), ejection fraction (OR per 1% increment; 0.96, 95%CI: 0.93–0.98, p < 0.001), female gender (OR 2.28; 95% CI: 1.31–3.98, p = 0.004), and heart rate (OR per 1 bpm increment; 1.03; 95%CI: 1.01–1.05, p = 0.007) were independent factors. LV and LA parameters on echocardiography worsened as MR severity progressed. Larger LV mass index and lower ejection fraction were independent determinant factors for MR-related symptoms. We should also pay attention to LV hypertrophy in patients with primary MR.