BACKGROUND Spinal anesthesia is the method of choice for cesarean section and in most cases causes hypotension. OBJECTIVE The aim of this study was to treat hypotension by ephedrine in order to prevent maternal and fetal complications, and also to determine the effective amount of ephedrine for reducing arterial hypertension in order to prevent its complications, including cardiac arrhythmias. METHODS This cross-sectional descriptive study was conducted on 131 patients. Mean arterial blood pressure (MAP) of the candidates for cesarean section in the supine position was measured and recorded as mean baseline blood pressure. 75 mg of lidocaine (5%) was used as spinal anesthesia, following which the average blood pressure was measured every 1 min. In the event of a decrease in the mean arterial blood pressure of at least 20% of the mean baseline blood pressure, ephedrine 0.1/mg/kg was injected intravenously and after 1 min of MAP was measured. RESULTS The prevalence of hypotension was 89.30%. 25.60% of patients with hypotension had 30-34.99% reduction in MAP compared to baseline MAP. 12% patients had 40% drop in their MAP. 4 min following spinal anesthesia, the incidence of hypotension reduced by 20%. The average dose of ephedrine required to reduce the incidence of hypotension was 20.5 mg. CONCLUSIONS Reduction in MAP following spinal anesthesia using lidocaine is common. Ephedrine at the dose of 20 mg is effective to reduce the incidence of perioperative hypotension.