Background: Preoperative ultrasound vein mapping is recommended for optimising arteriovenous fistula(AVF) creation for hemodialysis access. Routine Doppler ultrasound mapping significantly reduces immediate AVF failure rates and improves long-term patency compared to clinical examination alone. This study evaluates the reliability of vein mapping and its impact on surgical outcomes. Methods: This retrospective study reviewed autogenous AVFs created between 2020 and 2022 at a tertiary institution in Australia. Pre-operative vein mapping worksheets and operative reports were analysed to assess concordance between suggested and actual AVF creation sites. Outcomes included fistula maturation, occlusion rates, 30-day morbidity and mortality. Results: Of the 82 AVFs created, 36 were forearm (34 radiocephalic, 2 ulnobasilic) and 46 upper arm (31 brachiocephalic, 15 brachiobasilic) fistulae. Vein mapping suggested 46 radiocephalic, 32 brachiocephalic, and 4 brachiobasilic fistulae as suitable for creation. Discrepancies occurred in 31.7% of cases: 15 forearm cephalic veins required conversion to brachiocephalic fistulae, 3 forearm cephalic veins unexpectedly allowed for radiocephalic creation, and 12 cephalic fistulae needed conversion to brachiobasilic AVFs. Within 30 days, there was one fistula occlusion and one mortality. Additionally, five forearm fistulae failed to mature, necessitating further interventions. Conclusion: Preoperative vein mapping is valuable for planning AVF sites, but the high discrepancy rate suggests that intraoperative assessment is crucial. Discrepancies may result from arterial status, neuraxial blockade, venous dilatation, vein mapping techniques, and sonographer expertise. Incorporating intraoperative assessments could enhance site selection accuracy and optimize AVF outcomes.