Background: Surgical resection remains the most effective therapy for metastatic colorectal cancer confined to the liver, although the extrahepatic recurrence rate is high. Aim of the study: To develop a mammal model in order to investigate by which mechanisms liver surgery affects distant tumour recurrence. Methods: In this animal study the effect of partial hepatectomy (phX) on the development of tumour noduli in the lungs was evaluated. CC531 rat colon carcinoma cells were inoculated i.v. 24 h before, during or 24 h after surgery. Rat serum was obtained at different time-points after phX and added to in vitro CC531 cell cultures. Finally, phX was compared with an ileum resection (ilX). Results: phX leads to increased tumour noduli in the lungs, compared to Sham operation (p = 0.002), but only when performed directly before the injection of tumour cells and not when performed 24 h before or after the inoculation. Comparable results were obtained for ilX. No growth stimulation of tumour cells after incubation with rat serum, obtained at different time-points after phX, could be detected in vitro. Conclusion: Not only phX, but also surgery, in general promotes distant tumour recurrence exerting the effect during the early phase of tumour cell adhesion and not during tumour outgrowth. (C) 2007 Elsevier Ltd. All rights reserved.