BACKGROUND Spinal anesthesia is used as a common anesthetic technique in many routine and outpatient surgeries. OBJECTIVE The aim of this study was to determine the effect of phenylephrine on maternal hemodynamic changes during spinal anesthesia for cesarean delivery. METHODS This double-blind randomized controlled trial was conducted on 116 pregnant women candidate for the elective cesarean section through spinal anesthesia in the Shahid Akbarabadi Hospital, Tehran in 2019. The eligible women were randomly divided into the intervention (phenylephrine; n = 58) and control (normal saline; n = 58) groups. The data collection tool was a checklist, including the demographic and clinical variables, such as age, height, weight, body mass index, gravid, gestational age, Apgar score of 1 and 5, systolic blood pressure, diastolic blood pressure, heart rate, mean arterial pressure, SPO2, PH of the umbilical cord, PCO2, HCO3, base excess, nausea, and vomiting. Data were analyzed using SPSS 24 software and P value < 0.05 was considered as significant. RESULTS The intervention and control groups showed a significant difference in terms of the PH of the umbilical cord, PCO2, and nausea and vomiting (P value < 0.05). The results of the repeated measure ANOVA test showed a significant statistical difference between the intervention and control groups at different time points in terms of arterial pressure, systolic and diastolic blood pressures (P value < 0.05). CONCLUSIONS Phenylephrine is effective in the prevention of some complications, like reducing mean arterial pressure, systolic and diastolic blood pressures, nausea, and vomiting during spinal anesthesia for cesarean delivery. Therefore, these drugs can be used based on maternal hemodynamic status during spinal anesthesia for cesarean delivery.