Abstract: The present invention relates to a breath analyzing system and method. In particular the invention relates to a breath analyzing system and method arranged to provide tracer-aided classification of the presence of a breath intoxicating substance above a limit concentration and providing status to a user about the progression of the classification. The method/system detects a peak in the tracer signal and defines an evaluation period corresponding to the duration of the peak. Measurements classification of the concentration of the intoxicating substance is used for the evaluation period, and if required to achieve a result, for a plurality of evaluation periods.