The aim of the study was to evaluate the effect of a lidocaine-prilocaine cream (EMLA cream, Astra) in relieving pain during arterial cannulation. The study had a random, double-blind, placebo-controlled design and included altogether 90 patients. All the patients were premedicated with an opioid before cannulation. An EMLA application time of 60 minutes was used in 60 patients (30 EMLA/30 placebo) and there was no difference in the pain reaction measured on a visual analogue scale (VAS) or on an observer's verbal scale. The study was extended with a further 30 patients (15 EMLA/15 placebo) with an application time exceeding 90 minutes. Between these groups pain experience measured by VAS did not show any significant difference although the mean value was lower in the EMLA group. Observer ratings showed a significant (p less than 0.01) difference in distribution towards lower ratings in the EMLA group. In conclusion EMLA was found to have a weak, but measurable effect when the application time exceeded 90 minutes but not after 60 minutes.