In this paper a procedure for SAR (specific absorption rate) testing of wireless devices with simultaneous transmission in multiple bands is presented. The approach of this test procedure is to measure SAR for the transmitters in the device separately, add the measured SAR distributions and then finally calculate the 1 g and 10 g mass averaged SAR from the resulting distribution. The procedure has been tested successfully on a number of devices including a GSM mobile phone with an integrated long-range Bluetooth transmitter.