Abstract: The coffee preparation unit comprises a simplified injection group consisting of an assemblage of plastic elements attached to the lower plate (12) of its front portion (11). This group consists of a crosspiece (70) covered by an injection element (60) on an upper distribution chamber (63), which is traversed by a plurality of longitudinal channels communicating with a spray (51) which is attached to the front portion of the injection piece (60). The container holder (55) is attached directly to the lower plate (12) of the front portion (11). The coffee preparation unit also comprises an individual heater (46) for each coffee preparation post, with a flexible tube serving as a hydraulic inlet (47). The invention is of interest to manufacturers of professional "espresso" coffee machines.