Background : Post-spinal anesthesia hypotension is the most common incident, approximately 15 - 33% with each spinal anesthetic injection (Mercier et al., 2013).Post - spinal anesthesia hypotension was influenced by several factors, there were sympathetic block nerve height, patient position, Body Mass Index, length of operation, prehydration fluid, location of stabbing, and used of vasopressor Aim: To investigated the factors that most influence of hypotension in patients with spinal anesthesia. Methode: This retrospective study was carried out 80 medical records with purposive sampling at Soeradji Tirtonegoro Hospital Klaten, Center of Java. The data collectedincludes symphatetic block nerve height, patient position, Body Mass Index, length of operation, prehydration fluid, location of stabbing, and used of vasopressor.Data were analyzed using Chi-Square test and Logistic Regression test. Result: Incidence of hipotension in patient with spinal anesthesia was 56.25%. Factors influencing hypotension were sympathetic block height (OR = 3.391; 95% CI = 1.121-10.262), BMI (OR = 4,166; 95% CI = 1,625-10,676), prehydrated fluid (OR = 0.339; 95% CI = 0.135 -0,850), location of stabbing (OR = 0,136; CI 95% = 0,016-1,145) and use of vasopressors (OR = 0,303; CI 95% = 0,116-0,789) with p <0,05, while position factors and duration of operation have no effect . The factors that most influencedincidence of hypotension in patients with spinal anesthesia are prehydration fluids with a significance value of 0.002 and Exp (B) 8.221. Conclusion: Factors that influence the incidence of hypotension in patients with spinal anesthesia were namely sympathetic block height, BMI, prehydration fluid, location of stabbing, and use of vasopressors.