The advent of efficient, safer, economical anaesthetic drugs and techniques has seen a rise in the incidence of lower segment caesarean sections (LSCS) worldwide. In the Indian subcontinent, subarachnoid block is the most popular anaesthetic technique practiced for lower segment caesarean sections. However, it is associated with some unwanted effects like hypotension, nausea, vomiting and perioperative shivering. As stated by various studies, 20-55% of patients undergoing subarachnoid block (SAB) experience perioperative shivering1 . This causes discomfort, especially as the patient is conscious after subarachnoid block during caesarean section. Shivering is an involuntary muscle activity1 leading to an increase in oxygen consumption and consequently hypoxemia, lactic acidosis, catecholamine release and potential hemodynamic instability1, 2. Shivering interferes with monitoring devices2 , raises intracranial and intraocular pressures, raises the basal metabolic rate by 100 – 300%2 . In the postoperative period, it exacerbates postoperative pain, discomfort and causes stretching of sutures and thereby adversely affects wound healing3 . In caesarean sections, it can hamper breastfeeding and thereby impede mother child bonding1,2.Many pharmacological and non-pharmacological methods are used to prevent and control perioperative shivering. The pharmacological options include meperidine4 , buspirone5 , nefopam5 , clonidine5 , alfentanil5 , dexmedetomidine5 , tramadol6 and non-pharmacological measures1, 17 include warmers, blankets and warm intravenous fluids. The mechanism of shivering under subarachnoid block remains unclear7 , but a definitive role of 5- hydroxytryptamine (5HT) and its pathways has been identified8 . This led to the belief that 5HT3 antagonists like ondansetron and granisetron7, 10 prevent perioperative shivering. This study aims to determine the efficacy of prophylactic granisetron versus ondansetron, both 5HT3 antagonists in preventing perioperative shivering in parturients undergoing elective LSCS under SAB.