This study is going to evaluate the effect of intravenous midazolam on duration of sensory and motor block in spinal anesthesia. This study will be a double blind clinical trial on 36 candidates of elective lower abdomen and lower limb surgeries under spinal anesthesia in Alzahra Medical Center (Isfahan, Iran). Patients who meet the inclusion criteria such as age between (20-60) years old, American Society of Anesthesiologists classification (ASA) of I and II, no contraindication for the consumption of midazolam or benzodiazepine and no history of alcohol or other substance abuse will be enrolled in this study. Patients will be selected by simple sampling and randomized into two groups of 18 patients each by randomization software. All patients will receive 10 cc/kg Ringer’s lactate serum before spinal anesthesia. Spinal anesthesia will be performed by 2 ml of lidocaine 5% in sitting position at L3-L4 or L4-L5 intersegments. The subjects in the first group will receive 0.03 mg/kg midazolam and 1 μg/kg fentanyl intravenously with the time interval of five minutes. Patients in the second group (control group) will receive normal saline (2cc) plus 1 μg/kg fentanyl intravenously with the same time interval. An anesthesiologist, who will not be involved in the study, prepares the study solutions. Therefore, patients and investigators will be blinded to the patient group assignment. The highest dermatome level of sensory blockade, time to achieve maximum motor and sensory block level, duration of sensory and motor block and any side effect (regarding hypotension, nausea, vomiting) will be measured by an investigator. Moreover, heart rate, systolic and diastolic blood pressures, arterial oxygen saturation and sedation score will be recorded at five minutes before surgery and later every five minutes during the surgery.