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.To investigate efficacy and complications of PALs in extremely preterm neonates.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.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.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.