Radial arterial punctures are often performed in the emergency department to assess ill patients. However, these punctures are painful and can create anxiety in patients. In our hospital, physicians conventionally use the standard 23G needle attached to a syringe to obtain radial arterial blood. Smaller gauge, shorter and sharper needle has been shown to produce less pain. The common insulin syringe with its attached short 29G needle fits this description. The main objective of this study was to compare the degree of pain experienced during radial arterial punctures performed using the 29G common insulin syringe to that of the standard 23G needle. Healthy volunteers were recruited to receive bilateral radial arterial punctures. They were assigned to receive either the insulin or the standard needle on the right or the left hand as the first puncture using block of 4 randomization. Allocation concealment was achieved using opaque sealed envelopes. For each volunteer, a single doctor performed both punctures. The primary outcome was the pain score measured on a 100mm visual analog scale (VAS) and the secondary outcomes were immediate complications following the procedure and failure to obtain at least 0.5ml of blood in a single puncture. Both the volunteers and outcome assessors were blinded to the type of needles used. Fifty healthy volunteers (44% males) were recruited in the study. The mean age is 32.2 years. One patient withdrew from the study after the first puncture (standard needle) but is included in the analysis. The mean VAS score (± SD) using the insulin needle was lower than the standard needle, 22.6 (±21.9) mm versus 38.5 (±23.7) mm; p<0.0001. There was no difference in pain score between the two needles in relation to which hand was used (p=0.67) or whether the puncture was the first or the second (p=0.42). Bruising was immediately observed in 24% of punctures using the standard needle versus 0% using the insulin needle. Failure to obtain blood by a single puncture was observed in 7 (14%) punctures by the standard needle but only 3 (6%) by the insulin needle. Radial arterial puncture performed using the 29G common insulin syringe is associated with less pain, fewer immediate complications and fewer procedural failure rates.