Spinal anaesthesia is a recently accepted technique for PCNL. Vasopressors for prophylaxis and treatment of spinal hypotension have grown in popularity in recent years. The aim of our study was to evaluate the effectiveness of two different bolus doses of nor-epinephrine given pre-emptively for prevention of hypotension during spinal anaesthesia in patients undergoing PCNL and also to evaluate any associated adverse effects. A total 60 patients undergoing PCNL under spinal anaesthesia were enrolled in the study to receive either prophylactic nor-epinephrine bolus 10 µg (group A) or 15 µg (group B) immediately after spinal anaesthesia. Only one patient in group A developed hypotension requiring a rescue dose of vasopressor. 4 patients in group B developed systolic hypertension which settled without requiring intervention. Fall in blood pressure (systolic, diastolic and mean) were comparable between two groups. Maximum hypotension was encountered after the patient was put in prone position from supine position. From the above study we concluded that both 10 and 15 µg of Norepinephrine were effective in preventing hypotension. The dose of 15µg did not have any added benefit; rather it led to a statistically significant incidence of hypertension; which could prove hazardous in patients with pre-existing hypertension. Thus a bolus dose of 10 µg of Norepinephrine proved to be a good preventive measure against hypotension with reduced incidence of adverse effects.