Thoracic splanchnic nerves are splanchnic nerves that arise from the sympathetic trunk in the thorax and travel inferiorly to provide sympathetic innervation to the abdomen. The nerves contain preganglionic sympathetic fibers and general visceral afferent fibers. The present study was planned to assess the level of origin. Also to study the pattern of formation of the greater splancnic nerve in adult cadavers to overcome the failure rate in sympathectomy procedures. The study was planned on 20 cadaveric subjects. During dissection of thorax after the removal of the lungs the sympathetic chain was cleaned and the ganglia were defined. The origin of the greater splanchnic nerve from different ganglia and its formation were noted. The approval of the Institutional ethical committee was taken for the present study. From the present study the data gathered will be helpful for students as well as surgeons for a better outcome of the thoracic splanchnicectomy. Also in thoracolumbar sympathectomy the sympathetic chain has to be removed upto the highest point of origin of greater splanchnic nerve to overcome failure rate in sympathectomy.