Our objective was to evaluate our experience with the Advanced Breast Biopsy Instrumentation system (ABBI) in non-palpable breast lesions in a prospective study from July 1998 to November 2000. The ABBI system was included in a protocol for BIRADS 4 non-palpable, small (<15 mm) breast lesions. Digital radiographs of both specimen and biopsy cavity were obtained to validate the procedure. A total of 255 ABBI biopsies were performed in 254 patients. In 251 cases the lesions were successfully removed (98.4%). Mammographic lesions consisted of 176 cases of microcalcifications (69%), 51 cases of architectural distortions (20%) and 28 cases of nodules (11%). Seventy-two carcinomas were diagnosed (28.2%). Affected margins were found in 41 cases (56.9%). Residual tumour was seen in 31 patients (43%). Seventeen borderline results and 33 benign architectural distortions obviated further procedures. The complication rate in 10 cases was as follows: 3 wound infections; 4 haematomas; and 3 vasovagal reactions. The main utility of the ABBI system is to allow a reliable diagnosis in complex lesions, such as small clusters of microcalcifications and especially architectural distortions. Surgery can be avoided for borderline cases if the lesion is completely removed and free margins are obtained in the pathology study. Therapeutic use is controversial and can be applied only in selected cases.