The nature of the invasive growth pattern and microvessel density (MVD) have been suggested to be predictors of prognosis in primary colorectal cancer (CRC) and colorectal liver metastases. The purpose of the present study was to determine whether these two histological features were interrelated and to assess their relative influence on disease recurrence and survival following surgical resection. Archival tissue was retrieved from 55 patients who had undergone surgical resection for primary CRC and matching liver metastases. The nature of the invasive margin was determined by haematoxylin and eosin (H&E) histochemistry. Microvessel density was visualised using immunohistochemical detection of CD31 antigen and quantified using image capture computer software. Clinical details and outcome data were retrieved by case note review and collated with invasive margin and MVD data in a statistical database. Primary CRCs with a pushing margin tended to form capsulated liver metastases (P<0.001) and had a significantly better disease-free survival than the infiltrative margin tumours (log rank P=0.01). Primary cancers with a high MVD tended to form high MVD liver metastases (P=0.007). Microvessel density was a significant predictor of disease recurrence in primary CRCs (P=0.006), but not liver metastases. These results suggest that primary CRCs and their liver metastases show common histological features. This may reflect common mechanisms underlying the tumour-host interaction.