Background: Arterial catheterization is a routine procedure in extremely preterm neonates. Umbilical arterial catheters (UACs) are typically used for this purpose, but life-Threatening complications have been described. Peripheral arterial lines (PALs) might offer a valuable alternative, but their feasibility in extremely preterm newborns is unclear. Purpose: To investigate efficacy and complications of PALs in extremely preterm neonates. Methods: Retrospective analysis of patients born below 26 weeks of gestation in 2011-2014 (cohort 1, UAC as primary arterial access) and 2015-2019 (cohort 2, PAL as primary arterial access). Arterial line placement during their first 14 days of life, duration of arterial access, reasons for discontinuation, and long-Term complications were recorded from health records. Results: In total, 161 of 202 newborns had an arterial line during their first 14 days of life. In cohort 2, the life span of a PAL was significantly longer than that in cohort 1. Signs of dysfunction were the primary reason to discontinue a PAL. Signs of peripheral ischemia were present in 36 of 105 cases (34%) when the PAL was removed but persisted in only 2 patients. UAC-Associated persistent ischemic damage occurred in 2 of 97 patients. Implications for Practice and Research: PALs are a valuable alternative to UACs even in preterm newborns below 26 weeks of gestational age. A special focus on ischemic complications is warranted. Prospective, multicenter studies to verify safety and efficacy of arterial line management and complications in extremely preterm infants are warranted.