Colorectal cancer is one of the most common forms of cancer in the Western world. A wide variety of prognostic factors for colorectal cancer have been identified. There is, however, a paucity of literature addressing the influence of multiple primary carcinomas on prognosis. We conducted the present study in order to investigate the influence of second or multiple primary tumours on the prognosis of colorectal cancer patients. From 1992 to 2005, 1500 patients underwent surgery for colorectal cancer at the University Hospital of Luebeck. Of these, 276 patients (19%) had multiple primary malignant tumours. We performed statistical analyses only on patients who underwent surgery with curative intent in order to minimise additional prognostic factors. The patients were divided into groups according to the time of multiple primary tumour occurrence. Data were analysed for various variables. We did not detect any significant differences in survival either between the various groups or between patients with and without multiple primary tumours. The presence of multiple primary carcinomas is not an independent prognostic factor in patients with an index tumour of the colorectum. Multiple primary tumours are thus not necessarily associated with a poorer outcome and patients should receive curative intent surgery and appropriate follow-up care.