Needle aspiration with immediate cytological reporting has been practised in a breast clinic for one year. Patients benefit by receiving immediately the provisional diagnosis and, when indicated, appointments for metastatic surveys. Close co-operation between surgeon and cytologist has resulted in increased skill in aspiration, better preparation of samples, and greater accuracy in interpretation of reports. Since 5% of clinically benign lesions have proved malignant, even on immediate reporting, we would recommend cytological examination of all breast lumps.