The standards relating to testing of metal detectors for demining operations are developing well, including (but not limited to) CEN Working Agreement CWA14747:2003, UNMAS Mine Action Standards and others. However, for developing multisensor mine detectors there is no agreed standard method of testing. ITEP, the International Test and Evaluation Program for Humanitarian Demining, is currently drawing together several nation's experience of testing multisensor mine detectors into a "best practice" document that could be used as the basis for standardised testing. This paper outlines the test methodology used during recent multisensor mine detector tests and discusses the issues that have arisen and lessons learned. In particular, the requirements for suitable targets, careful site preparation, measurement of appropriate environmental factors and methods of maximising useful results with limited resources are highlighted. Most recent tests have used a combined Metal Detector (MD) and Ground Penetrating Radar (GPR), but other sensor systems will be considered. An emerging test methodology is presented, along with an invitation for feedback from other researchers for inclusion into the "best practice" document.