We have reviewed the histological features and clinical outcome in 32 women with phyllodes tumours of the breast diagnosed in Nottingham between 1975 and 1990. We assessed 23 tumours as histologically benign, four as borderline and five as malignant. After clinical follow up for periods ranging from 36 months to 221 months (median 135 months), six of 23 benign tumours have recurred locally; in all these cases the original tumours had been incompletely excised. There were no recurrences amongst 10 benign tumours in which excision had been complete. Benign tumours which recurred showed a tendency to greater stromal cellularity and more pronounced stromal overgrowth than incompletely excised lesions which did not recur, but these differences were not statistically significant. The recurrent tumours resembled the respective original lesions histologically, except in one case in which two local recurrences were histologically malignant. The recurrent tumours were controlled by further excision or mastectomy in all cases and none have metastasized. All four borderline tumours were completely excised at initial surgery and none have recurred or metastasized. One of the five malignant tumours recurred within two months of incomplete excision, with widespread infiltration of the chest wall, although the patient died of unrelated causes. The other four malignant tumours have not recurred. We conclude that presence of tumour at the margins of the excised specimen is the major determinant of local recurrence in phyllodes tumours and that the histological features are of secondary importance. These findings are discussed in relation to other published series in the literature.