Background: vitamin D is a fat-soluble vitamin; it has skeletal and non-skeletal functions. The effect of Vitamin D on CV disease had several mechanisms including elevated PTH and Calcium-phosphate metabolism. It decreases the pro- remodeling of Angiotensin II on the cardiomyocytes. The Objectives: to study relation between serum levels of vitamin D and echocardiographic determinants of systolic and diastolic functions in patients with and without cardio-renal syndrome. Patients and Methods: prospective study was conducted on 90 patients of all age groups and both sexes, admitted to Ain-Shams University hospital. The study included 3 groups of patients: Group 1: systolic dysfunction and renal insufficiency (30 patients), Group 2: systolic dysfunction only (30 patients). Group 3: renal insufficiency only (30 patients), in addition 10 healthy controls were taken as controls. Patients were subjected to full comprehensive echocardiography and KFT with estimation of creatinine clearance, and Vitamin D level that was statistically studied against echocardiographic parameters of cardiac systolic and diastolic function. Results: our study found that, compared to patients with normal vitamin D level, patients with vitamin D deficiency (defined as having vitamin D level <20 ng/ml) had significantly higher ventricular thickness (IVS, PW and mean wall thickness) (P value < 0.001), and higher LV mass which seems to be linked eventually to worse outcomes with no significant impact on worsening Diastolic dysfunction. A ROC curve was done revealing a sensitivity of 80% for the mean wall thickness (≥ 10 mm) to identify patients with vitamin D deficiency. Conclusion: Vitamin D deficiency was associated with ventricular hypertrophy with worsening outcomes with no impact on diastolic function. Key words: