Abstract: An on-line somatic cell analyser and a method for measuring a somatic cell count (SCC) are provided. A flow cell is connected to a milking hose and admits a constant volume of sampled milk into the flow chamber. A probe with two electrodes is positioned in a zone of optimal sensing inside the flow chamber, and provides a modulated signal according to the number of sodium ions present in the sample. A control unit receives the modulated signal, generates an ion count, and compares same with a plurality of SCC thresholds for classifying the sample in a quality category. A set of parameters characterizing the respective quality category, as well as the presence of mastitis in the animal, are finally displayed.