Asthma is the most common cause of respiratory disability among children. Patients with severe bronchial asthma can experience cor pulmonale later in life, but little is known about the function of the right ventricle early in the disease. This study aimed to investigate the right ventricular function in children with bronchial asthma as detected by tissue Doppler echocardiography. This case-control study compared 60 asthmatic children ages 5 to 15 years between attacks (study group) with 60 apparently healthy children (control group). All the children were subjected to full history-taking, complete physical examination, measurement of peak expiratory flow rate (PEFR), chest x-ray, electrocardiography (ECG), echocardiographic examination, and both conventional and tissue Doppler study. The results of the tissue Doppler study examining the right ventricular diastolic function showed that peak E′ velocity (10.08 ± 2.8 cm/s), peak A′ velocity (5.7 ± 2.5 cm/s), E′/A′ ratio (1.77 ± 0.58 m/s), and isovolumetric relaxation time (IVRT) of the lateral tricuspid annulus (138.9 ± 30.7 m/s) among the asthmatic patients differed significantly from those among the control subjects (12.4 ± 2.3, 7.8 ± 2.1 cm/s; 1.58 ± 0.32, and 91.1 ± 32.6 m/s, respectively). In addition, the E′ velocity and IVRT of the lateral tricuspid annulus were significantly different among the mild, moderate, and severe cases (P < 0.001). It is concluded that although the clinical and conventional echocardiographic findings of the asthmatic children were apparently normal, the tissue Doppler echocardiographic study showed right ventricular dysfunction that is positively correlated with the severity of asthma. These findings signify the diagnostic value of tissue Doppler echocardiography for the early detection and monitoring of such deleterious effects among asthmatic patients.