Abstract: A method for leak-testing a plate heat exchanger is provided. The heat exchanger includes a plurality of primary plates, each primary plate having a long surface in which a plurality of primary channels are bored to ensure the circulation of a primary fluid; a plurality of secondary plates, each secondary plate having a long surface in which a plurality of secondary channels are bored to ensure the circulation of a secondary fluid, the primary and secondary plates being stacked on top of each other alternately. The method includes at least one inspection-testing step during which eddy current testing probes are moved along the primary and/or secondary channels, the primary and secondary plates being diffusion-welded onto each other in such a way that the primary and/or secondary channels have continuous perimeters allowing circulation.