Background and Aims The perfusion index (PI) which is the ratio of the pulsatile blood flow to the non–pulsatile or static blood in the peripheral tissue, represents a  measure of peripheral perfusion obtained from pulse oximeter of Masimo SET(signal extraction technology) type. In spinal anaesthesia sympathetic blockade typically occurs before the onset of anaesthetic (sensory and motor) effects. Sympathetic blockade causes local vasodilatation leading to rise in PI in legs. So PI via toe can detect proper spinal anaesthesia. Methods Two probes placed one on index finger and other on 2^nd toe, to measure the PI in 30 elective LSCS. Intrathecal 12.5mg hyperbaric bupivacaine was administered in sitting position then immediately patiens were made to lie supine with 15 degree left lateral tilt to avoid supine hypotension of pregnancy. PI via finger, toe and percentage changes over base line were calculated and analysed before and after spinal anaesthesia. Results PI via toe increased significantly(p<0.0001) soon after administration and reached a plateau within 5 min, whereas PI finger did not change much. Median anaesthesia levels by cold test were T6 at 15 min. In 2 failed cases no change in baseline PI. Conclusion our results suggests that PI is early and non–invasive indicator of proper spinal anaesthesia onset. However final results will be shown at the time of presentation