Compact Groups of at least 4 galaxies of comparable luminosity are the densest galaxy associations known at present. The compactness of these groups is so high that the typical projected separations between galaxies are of the order of their own diameters, hence their space densities can exceed those of the cores of rich clusters. The combination of their very high number densities and low velocity dispersion makes CGs the ideal site of galaxy mergers. We present here a new catalogue of Compact Groups automatically extracted from the 2MASS extended source catalogue. We compare the properties of these CGs with those previously identified from other observational and simulated samples, including the original sample defined by Hickson (1982). The new velocity-filtered Compact Group catalogue is the largest at present with well-known selection functions, automatic selection by stellar mass and signs of mergers. This catalogue appears as the best laboratory to study physically dense groups of 4-10 galaxies of comparable luminosity.

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