Aim: To compare the success rates and postoperative pain levels of caudal epidural block (CB) applications using ultrasound-guided out-of-plane technique and in-plane techniques in pediatric hypospadias surgery. Methods: One hundred sixty-two patients who underwent pediatric hypospadias surgery were randomized to either the in-plane or out-of-plane ultrasound-guided CB. The primary outcome was the success rate of CB. Secondary outcomes included postoperative pain levels (FLACC score), the first analgesia requirement time, the total amount of paracetamol consumption, and complications. Procedural data were collected by blinded observers. Results: There were differences in the primary outcome of the number of needle attempts 87.8% vs. 56.3%, p<.001), the success rate at the first entry (93.9% vs. 62.5%, p<.001), the visualization rate (90.2% vs. 31.3%, p<.001), a local anesthetic (LA) spread rate (87.8% vs. 46.3%, p<.001), and the duration of block application (41.44 ± 25.87 sec vs. 78.11 ± 43.13 sec, p<.001), respectively, between the in-plane and out-of-plane groups. There were also differences between out-of-plane and in-plane FLACC scores at the 12th and 24th hours (p=.024 and p=.012, respectively), the first analgesia requirement time (p=.009), and the total amount of paracetamol consumption (p=.018) in 24-hour pain ratings. There were no differences in complications. Conclusion: Ultrasound-guided in-plane technique is an alternative technique that is superior to the out-of-plane technique for its success rate and postoperative analgesia.