Hypotension, a common, but dreaded complication in the post-operative period is dealt with in detail. Pathophysiology is first described comprehensively, describing cardiac, vascular, humoral and microcirculatory factors in causing hypotension. Aeitiological factors like haemorrhage and sepsis leading to hypotension are dealt with in detail. Cardiac factors like infarction, endocrinologic factors like hypothyroidism, and rare conditions like drug related hypotension are also mentioned. Consequences, prevention and management of hypotension are dealt with in detail. Guidelines are given on administration of crystalloids, colloids and blood transfusion in post-operative hypotension. Monitoring of the patient and the use of vasopressor agents are described systematically.