Background. Infiltration of the skin and subcutaneous tissue with local anesthetic solutions may cause transient pain and discomfort, Heating local anesthetic solutions to body temperature has been suggested as a way of reducing the pain associated with injection. We designed a double blind crossover volunteer study to investigate the effect of warm- ing lidocaine on the pain associated with subcutaneous injection Methods Participants were 40 healthy adult volunteers, 22 years of age and older, and they were the medical, nursing staff and medical students They underwent 1ml subcutaneous injections of the study agent through 25-gauge nee- dles Following a standard crossover protocol, room ternperature lidocaine(20 ) was injected into one midvolar forearm and bady temperature lidocaine(37 ) into the opposite arm Pain assessed by visual analogue pain scores and 'volunteer's comparison of pain on injection Results Twenty-six volunteers thought that lidocaine at 20%was more painful and four thought that lidocaine at 37 was more painful, ten volunteers did not express a difference. Median pain score for injection at 20 was 37 and at 37 was 35.5 Difference of two median scores was 6.5 Condusion. The simple procedure of warming to body temperature reduced the pain associated with subcutaneous injection of lidocaine It is an inexpensive and practical method that should be considered for routine use in the ED