Background: Long peripheral catheters are peripheral intravenous catheters of 6–15 cm in length. They are commonly inserted into the forearm, antecubital fossa or upper arm using a direct Seldinger technique. They have proven to be valuable for peripheral intravenous catheters, particularly in patients with difficult intravenous access. Methods: We conducted a systematic review of studies reporting the use of long peripheral catheters. The following keywords were used: ‘long’, ‘Seldinger’, ‘guidewire’, ‘peripheral’, ‘venous’, ‘intravenous’, ‘IV’, ‘vascular’, ‘cannula’ and ‘catheter’. Results: Three hundred forty-one publications were identified; 16 were included in the systematic review. There were 11 adult studies and 5 paediatric studies documenting 1288 long peripheral catheters in 1271 patients. Majority of studies (12/16) were conducted in acute care settings, (emergency department, n = 6; intensive care unit, n = 3; high dependency unit, n = 1; surgical unit, n = 2). The most frequently studied long peripheral catheter was 8 cm in length and 20 G in size. Nine studies recruited patients with difficult intravenous access; 11 studies used ultrasound guidance. Insertion success rate and mean procedural time ranged between 86% and 100% and 8 and 16.8 minutes, respectively. Average catheter duration ranged between 4 and 14.7 days (mean) and 1.1 and 9 days (median). Catheter failure occurred in 4.3–52.5% of long peripheral catheters, with leakage, infiltration and dislodgement being the most frequent causes of failure. In 3 randomised controlled trials, long peripheral catheters outperformed peripheral intravenous catheters in terms of duration and failure rate. Conclusion: Long peripheral catheters are safe and reliable in both adults and children. In addition, long peripheral catheters may provide improved quality of care over peripheral intravenous catheters for multi-day intravenous therapy.