In a retrospective study 678 patients who underwent (modified) radical mastectomy between 1970 and 1986 were analysed. By comparing the groups of patients who experienced local recurrence, regional recurrence or distant metastasis during follow-up with patients who remained free of disease, we have tried to gain some insight into the significance of local recurrence. By looking at the prognostic factors and the disease-free period there is hardly any difference between the patients with either a local, regional or distant recurrence. Actuarial survival of patients with local recurrence is slightly better than the survival of patients with distant metastasis (P = 0.009). From our results and from the literature we conclude that an isolated local recurrence after mastectomy for breast cancer is, in most cases, a first manifestation of metastatic disease. Probably only a minority of the local recurrences is caused by tumour cells left behind in the operation field.