A prospective trial was performed to assess the accuracy of Tc-99m MIBI scintimammography in 63 women (mean age 65, range 33-85 years) with suspected recurrent breast cancer in the breast and/or loco-regional tissues. All patients had been diagnosed with breast cancer 1-23 years before the scintimammography. A total of 27 breasts had been removed by mastectomy so scintimammography was compared with mammography in the remaining 99 breasts. Pathological follow-up of patients confirmed 33 sites of recurrent disease within the breast, 26 (78%) were identified by scintimammography and 14 (42%) by mammography; 30 (90%) were positive on one test or the other. In addition Tc-99m MIBI scintimammography identified 10/16 (63%) of axillary lymph nodes with recurrent tumour and 4/6 sites of recurrent tumour present elsewhere. Tc-99m MIBI scintimammography is more accurate in identifying recurrent disease in the breast than mammography and can identify loco-regional recurrence outside of the breast.