Eighty-four phyllodes tumours (71 benign, eight borderline and five malignant) diagnosed over a 16-year period were studied retrospectively, to assess the diagnostic value of the pre-operative modalities used. Mammography and ultrasound appearances were non-specific. The possibility of phyllodes tumour was raised in only 23% on fine needle aspiration cytology, and in 65% on core biopsy. Accuracy was better in smaller tumours, suggesting that larger tumours need more samples. For phyllodes tumours whose growth was measured, almost all had growth rates greater than for growing fibroadenomas. The pre-operative diagnosis of phyllodes tumours is difficult, and rapid growth and/or large size of apparent fibroadenomas may be the only imaging findings to suggest phyllodes tumour. It is important to review most fibroadenomas with ultrasound, to assess the rate of growth if any. Whole breast ultrasound showed that nearly one third of women with phyllodes tumours had concurrent fibroadenomas.