This study aimed to test the hypothesis that lymphovascular invasion adds prognostic information to histological grade and tumour size in node-negative invasive carcinoma of the breast. Lymphovascular invasion was assessed in haematoxylin and eosin tumour sections from 2760 patients with node-negative invasive breast carcinoma treated with definitive surgery. Patients were divided into two groups: 990 in the no adjuvant therapy series (diagnosed in 1974-1988) with median follow-up of 13 years; and 1765 in the selective adjuvant therapy series (1988-2000) with median follow-up of 6.8 years. Lymphovascular invasion was identified in 19% of tumours and was associated with larger tumour size, higher histological grade and younger age. Overall, survival was associated on multivariate analysis with lymphovascular invasion, histological grade and tumour size in both patient series, and with histological type in the no adjuvant therapy series. In conclusion, lymphovascular invasion is an independent prognostic factor in node-negative breast cancer and should be considered in decisions about adjuvant treatment in this group of women.