Problem statement: The purpose of this study was to evaluate the onset and duration of sensory and motor block as well as operative analgesia and adverse effects of Dex Metedo Midine (DXM) or fentanyl given intrathecally with plain 0.5% bupivacaine for spinal anesthesia. Approach: seventy six patients classified as American Society of Anesthesiologists (ASA) status I, II and III scheduled for vaginal hysterectomy, vaginal wall repair and tension free vaginal tape were prospectively studied. Patients were randomly allocated to receive intrathecally either 10 mg isobaric bupivacaine plus 5 µg dexmetedomidine (group D n = 38) or 10 mg isobaric bupivacaine plus 25 mg fentanyl (group F n = 38), the onset time to reach peak sensory and motor level, the regression time for sensory and motor block, hemodynamic changes, and side effects were recorded. Results: Patients in group D had significant longer sensory and motor block times than patients in group F. the mean time of sensory regression to S1 was 274±73 min in group D and 179±47 min in group F (P < 0.001). The regression time of motor block to reach modified Bromage 0 was 240±60 min in group D and 155±46 min in group F (P< 0.001). The onset times to reach T10 dermatome and to reach peak sensory level as well as onset time to reach modified Bromage 3 motor block were not significantly different between the two groups. Conclusion: In women undergoing vaginal reconstructive surgery under spinal analgesia, 10 mg plain bupivacaine supplemented with 5 µg dexmetedomidine produces prolonged motor and sensory block compared with 25 µg fentanyl.