A washer machine for medical instruments comprises a washing chamber, at least a sliding loader trolley at least to load the medical instruments into the washing chamber and a washing device to wash the medical instruments, comprising a multiple connection unit and a plurality of flexible washing pipes connectable to the aperture of the medical instrument to be washed. The multiple connection unit comprises a free multiple connector, autonomous and unconstrained from the sliding loader trolley and connectable to said flexible washing pipes, and a static and fixed multiple counter-connector disposed in the washing chamber. A releasable manual mechanical clamping device is provided for the selective connection of the free multiple connector to the static and fixed multiple counter-connector.
