SummaryBackgroundLocalisation of the radial nerve (RN) in the spiral groove by previously reported methods has a wide range and is generalised. The objective of this study was to establish a method unique to a patient to accurately localise the nerve.MethodsThe distance between RN at the midpoint of the spiral groove (D) and the tip of the olecranon (O) was compared with the most distal wrist flexion crease and fingertips on 100 healthy volunteers. The RN was found by ultrasound examination.ResultsThe mean distance from O to D was 16.22 cm (12.5–20.5 ± 1.55), and mean distances from wrist crease (WC) to second, third, fourth and fifth fingertips were 17.79 (14–20 ± 1.28), 18.66 (15–21 ± 1.32), 17.71 (14.5–20.5 ± 1.32) and 15.62 (12.5–20.5 ± 1.34) cm, respectively. With regards to O–D distance, the strongest relationship was obtained for the distance between the fifth fingertip to the WC (r = 0.708, p < 0.001). This relationship was stronger among females than males (p < 0.001).ConclusionThe course of the RN can be easily found at the upper arm by this method, which is unique to a patient.The translational potential of this articleThis study presents a new and individualised approach to accurately predict the location of the RN in the spiral groove. This method is clinically relevant and can be used to guide the surgical explorations or expedite interventional methods.