Since bacterial infection in newborns must be treated as specifically and as early as possible, it is important to confirm a diagnosis of suspected infection based on clinical symptoms and to take possible pathogens into consideration when choosing therapy. RDS and septicemia with Group B streptococci can present very similar clinical symptoms, but leucopenia on the first day of life is most probably an indication of septicemia with Group B streptococci. Septicemia caused by other pathogens, however, usually has a much later onset. In the days following birth a raised cardiothoracic index indicates RDS. Other differential criteria are being investigated.