OSA is one of the factors leading to cardio-vascular remodeling. This study was planned to compare pulmonary artery pressure and morphological parameters of left-sided chambers of heart between two groups—severe OSA and a control group. 30 consecutive subjects with severe OSA diagnosed through overnight video-synchronized attended polysomnography and 30 consecutive subjects having “low risk for OSA” were recruited in this study. The latter group served as control group. Informed consent was taken and they were screened for exclusion criteria. Their medical history was obtained and anthropometric parameters were measured. 2-D Echocardiography was done by a cardiologist following standard guidelines. Both groups were comparable with regard to age (52.2 ± 10.1 years cases; 54.5 ± 12.1 years controls; t = − 0.78; P = 0.43). 40% cases and 7% controls had history of systemic hypertension (χ 2 = 9.31; P = 0.002). Half of the OSA patients had mild to moderate tricuspid regurgitation while none among the controls. None of the subjects in either group ever had myocardial infarction. OSA subjects had larger left atrium (3.63 ± 0.43 vs. 3.16 ± 0.41 cm in control; P = 0.003), higher left ventricular end-systolic volume (53.25 ± 16.69 vs. 38.82 ± 9.36 ml in controls; P = 0.01), higher mean pulmonary artery pressure (19.41 ± 7.89 vs 14.91 ± 3.55 mmHg in controls; P = 0.04), thicker left ventricular posterior wall (1.25 ± 0.13 vs 0.65 ± 0.25 cm in controls; P < 0.001) after controlling for confounders like age, gender, body mass index and systemic hypertension. An index was calculated for the left atrial size and left ventricular volumes with body surface area. Among these indices, only left ventricular end systolic volume index was found to be higher among subjects with severe OSA after controlling for confounders like age, gender, body mass index and systemic hypertension. Severe OSA is associated with remodeling of pulmonary vasculature and left-sided chambers of the heart.