We describe a simple and effective technique for laying extracorporal telemetry radiotransmitters on lizards Aspidoscelis, by placing the radio transmitter in a backpack. To test the effectiveness of this technique, four males were equipped with backpacks-radio transmitter and released to continue their individual trace. Radio-transmitters lizards remained for 12 weeks and a visual assessment a priori suggests no negative effects by backpacks on natural behavior of lizardsCONACYT