OBJECTIVE: to assess the utility of peripheral venous lactate (PVL) in Emergency Department patients. METHODS: arteriovenous agreement was assessed in three subgroups: PVL <2 mmol/l, PVL ≥ 2 mmol/l to < 4 mmol/l and PVL ≥ 4 mmol/l. The predictive value of PVL to predict arterial lactate (AL) ≥2 mmol/l was assessed at different cut-off values. RESULTS: 74 samples were analysed. The venous-arterial mean difference and 95% limits of agreement for the subgroups were 0.25 mmol/l (-0.18 to 0.68), 0.37 mmol/l (-0.57 to 1.32) and -0.89 mmol/l (-3.75 to 1.97). PVL ≥2 mmol/l predicts AL ≥2 mmol/l with 100% sensitivity. CONCLUSION: PVL <2 mmol/l rules out arterial hyperlactatemia. As agreement declines in higher levels, arterial sampling should be considered.