Objectives: The heart and blood vessels are sensitive to the effects of excess thyroid hormones (THs). Echocardiography is an important investigative modality in detecting cardiac involvement in disease states and so was employed in finding out if the hyperdynamic state in thyrotoxicosis was associated with enhanced left ventricular systolic function. Methodology: Consultants in main hospitals in Enugu were requested to send in adult patients with thyrotoxicosis to the out patients department of UNTH, Enugu. The patients were recruited consecutively and diagnosis confirmed following clinical assessment and thyroid function tests. Echocardiography was done to assess enhanced left ventricular systolic function (indicated by any of these parameters VEF >75%, FS >42%, CO > 7 l/min, CI >4.3 l/min/m2, MVCF >1.9 cir/sec, PASV >120 cm/sec. Results: Thyrotoxicosis patients were leaner, had no significant difference in blood pressure when compared with controls. The patients also had significantly enhanced left ventricular systolic function when their FS (43.9%-p<0.05), CO (7.15l/min-p<0.05), and AOVMAX (144 cm/sec-p<0.05) were compared with controls. Values of free T3 also correlated positively with systolic echocardiographic parameters. Discussion and Conclusion: The effect of TH on the heart has led to interest in the therapeutic use of TH on cardiac diseases. Thyroid hormone could be used as replacement therapy in cardiac diseases in which there is background low thyroid hormone and poor systolic function or heart failure.