Method and platelet counting device

A method of counting thrombocytes contained in a blood sample, comprising: - mixing said sample with: o fluorescent labels capable of specifically binding with the platelets; and o an inhibitor of activation of said platelets; - introducing the sample (E) into a fluid chamber (CF) having at least one transparent face; - acquiring at least one digital image (IN) of said sample by fluorescence microscopy; and - counting thrombocytes (T) present in said or each image by computer image processing (0). An apparatus for carrying out this method.