Besides clinicopathological parameters, molecular markers can be very important, and further characterize colorectal carcinomas into chromosomally unstable, microsatellite instable and "CqG-island methylator phenotype" groups.To study the frequency of microsatellite instability using immunohistochemical evaluation of MLH1, MSH2, MSH6 and PMS2 proteins in colorectal carcinoma.122 colorectal carcinomas as well as in 69 paired liver metastases were evaluated. Additionally, prognostic and predictive potential of mismatch repair status was tested.Microsatellite instable phenotype was identified in 11.5% (14/122) of the tumours. There were no differences regarding staining intensity of tumour regions. Mismatch repair status was discordant in primaries vs. metastases in 20.2%. There was no difference in progression free- and overall survival according to mismatch repair status. The mismatch repair status was not predictive for survival within systemic therapy regimen groups.The subgroups of colorectal carcinomas could be evaluated in a larger and homogenised patient cohort to predict prognosis and response to therapy.