In order to overcome the difficulties of testing infrared imaging systems, an hardware infrared simulator has been developed. It consists of a panel of infrared micro-emitters, which simulates a real scenario generated by a computer software, the electronics and the optics required to allow the imaging system to see the scene, as it would come from the real world. A description ofthe main concepts involved, ofthe main components and ofthe results obtained, is given. To test a complete (optics, electronics, display, etc.) infrared imaging system the availability of a real scenario is needed, in which all the possible situations are present. This means that a very great variety of conditions should be satisfied. For instance, the natural or man made events, like forest fires, storms, volcanic eruptions, earth or air pollution, industrial factories, explosions, battlefields, launch of missiles, etc., should be present, and the unit under test should be in the conditions in which it really will be required to operate. This approach is obviously almost impossible to reach and in most of the situations it would be too expensive. In order to overcome these difficulties, it is possible to simulate, in laboratory, the required conditions: a scene can be projected toward the system under test (SUT), which can simulate the events that the system should be able to see. The projected scene should, at the same time, cover the full field of view of the SUT, have at least its angular resolution and the scene signal dynamic. At CREO laboratories a hardware simulator has been developed, which can satisfy most of the above mentioned requirements.