Juvenile idiopathic arthritis (JIA) is a systemic chronic inflammatory disease. Cardiac involvement as pericarditis, myocarditis and valvular disease is common in JIA. This study aims to assess left ventricular (LV) diastolic functions with tissue Doppler imaging (TDI) and to compare it with conventional Doppler echocardiography (pulse wave Doppler (PWD)) techniques in patients with active JIA. Forty-five patients with active JIA and 47 healthy age- and sex-matched controls were included in this study. Duration of disease ranged from 6 to 138 months (mean 49.59 +/- 31.25 months). In addition to PWD echocardiographic methods, TDI was performed to assess LV functions in all participants. On PWD echocardiography analysis, the JIA group had lower peak E velocity (p < 0.001), higher peak A velocity (p < 0.001) and more prolonged isovolumic relaxation time (IVRT) (p = 0.02). E/A ratio was found to be lower in patients with JIA than that in the control group (p < 0.001). Patients with JIA had a much higher E velocity trace integral (VTI) and A VTI when compared to controls (respectively p = 0.03, p = 0.04). Mitral annular early diastolic velocity (Em), among TDI parameters, was found to be lower in patients with JIA than that in the control group (p < 0.001). Em/Am (mitral annular late diastolic velocity) ratio was found to be lower in JIA patients compared with that in the control group (p < 0.001). There was an increase in IVRT in JIA patients compared to control group (p = 0.04). Though Em VTI was similar in the two groups, patients with JIA had a much higher Am VTI when compared to controls (respectively p = 0.48, p < 0.001). E/Em ratio was higher in patients with JIA than in the control group (p < 0.05). LV diastolic functions were impaired in patients with active JIA, in the absence of clinical evidence of cardiac disease. We have concluded that TDI solo, or jointly with PWD echocardiography, is valuable for the evaluation of diastolic functions in active JIA patients.