Introduction: Hypotension following spinal anaesthesia results from the sympathetic blockade and decreased cardiac output. Non?invasive blood pressure (NIBP) measurement is the standard method of monitoring intraoperative hemodynamics. Perfusion index (PI) is a relative assessment of the pulse strength at the monitoring site. PI can be used to assess the perfusion dynamics due to changes in peripheral vascular tone which is a non-invasive method to detect hypotension following subarachnoid block .Objective: This study was aimed to investigate the correlation between baseline perfusion index and incidence of hypotension following spinal anaesthesia and also determine the diagnostic characteristics of PI. Material & Method: This prospective observational study was conducted among 56 parturients undergoing cesarean deliveries under subarachnoid block at R. L. Jalappa Hospital and Research Centre, Tamaka, Kolar during the period from 1^st March 2023-31^st July 2023. The parturients aged 20-35yrs and undergoing caesarean delivery under spinal anesthesia. Patients with placenta previa, preeclampsia, gestational diabetes, cardiovascular or cerebrovascular disease, with BMI > 40 kg/m², Infection at local site, Lumbar spine deformity and patients refusal. Participants included in study after obtaining the informed consent and the hemodynamic parameters were measured which included mean arterial pressure, systolic blood pressure, diastolic blood pressure, saturation, heart rate and any adverse effects following spinal anaesthesia. Groups: two groups; group I with PI <3.5 and group II with PI >3.5. Results: The present study included tot al of 56 participants in present study with mean age of 24.6±3.54yrs. the cutoff suggested for PI was taken as 3.5. based on cutoff, group I included participants with <3.5PI and group II participants with >3.5PI.  There was significant higher incidence of number of hypotension episodes in group II patients compared to group I patients.(p<0.05)The area undercurve for PI was found to be 0.858, with p<0.05. the sensitivity and specificity of baseline PI with cutoff of 3.5 was found to be 69.82% and 90.22% respectively to detect hypotension. Conclusion: The Perfusion index can be used as a important tool for predicting the hypotension in apparently healthy parturient undergoing caesarean section. The parturients with PI of more than 3.5 are at a higher risk of developing the spinal anesthesia induced hypotension.