Background and Objectives: Dexamethasone has been shown to prolong the duration of analgesia when used as an adjuvant to local anesthetics in peripheral nerve blocks. This study aimed to compare the effects of ropivacaine alone and ropivacaine with dexamethasone on the onset and duration of sensory and motor block, as well as the duration of analgesia, in infraclavicular brachial plexus block for upper extremity surgeries. Methods: In this prospective, randomized study, 40 patients were allocated into two groups: Group R (n=20) received 20 mL of 0.5% ropivacaine with 2 mL normal saline, and Group D (n=20) received 20 mL of 0.5% ropivacaine with 8 mg dexamethasone. The onset and duration of sensory and motor block, duration of analgesia, postoperative pain scores, and rescue analgesic consumption were assessed. Results: The onset of sensory block (11.2 ± 2.9 min vs. 16.5 ± 3.8 min, p<0.001) and motor block (14.6 ± 3.5 min vs. 21.8 ± 4.7 min, p<0.001) was significantly faster in Group D compared to Group R. The duration of sensory block (738.6 ± 96.2 min vs. 512.4 ± 74.9 min, p<0.001), motor block (664.3 ± 88.7 min vs. 462.1 ± 63.5 min, p<0.001), and analgesia (875.2 ± 102.4 min vs. 589.3 ± 81.6 min, p<0.001) was significantly prolonged in Group D. Postoperative pain scores were lower, and rescue analgesic consumption was reduced in Group D (1.3 ± 1.0 vs. 2.4 ± 0.9, p=0.001). The incidence of adverse events was similar between the groups. Conclusion: The addition of dexamethasone to ropivacaine in infraclavicular brachial plexus block significantly enhances the onset and duration of sensory and motor block, as well as the duration of analgesia, compared to ropivacaine alone, without increasing the risk of adverse events.