Summary Background: When it comes to orthopedic surgeries involving the lower limbs, spinal anesthesia offers the most predictable block due to the strong sensory as well as motor block that it provides, with the benefits of avoiding the risks of general anesthesia. This study aimed for comparing intrathecal dexamethasone versus intravenous dexamethasone on quality of spinal anesthesia in lower limb orthopedic surgeries. Methods: We carried out this prospective randomized controlled study on 63 adult patients who undergoing orthopedic lower limb procedures under the influence of spinal anesthesia; they were randomized into three equal groups (each containing 21 patients): group C (control), group V (intravenous dexamethasone) and group S (intrathecal dexamethasone). The Visual Analogue Scale (VAS) was done at first admission to the PACU, then at 1, 3, 6,12, and 24 hours at rest and during movement with an assessment of complications postoperatively. Results: A significant longer duration of sensory block was revealed in group S compared to both group C and group V (191.43 ± 25.94, 109.52 ± 7.4, 110.67± 11.14, respectively). The visual analogue scale (VAS) was higher in control group at 1, 3, and 6 hours postoperatively, especially at 3 hours. A statistically significant difference existed between studied groups regards intraoperative complications (P<0.001) in control group Conclusion: Adding Intrathecal dexamethasone to bupivacaine in spinal anesthesia was associated with longer duration and level of sensory block, lower VAS and total amount of rescue analgesia with decreasing complications of spinal anesthesia as hypotension, shivering, and vomiting compared to intravenous route administration.