The aim of this study was to assess the usefulness of planar scintimammography (SM) with a high-resolution dedicated breast camera (DBC) compared to SPECT in unifocal and multifocal/multicentric primary breast cancer (BC) detection. DBC planar SM and conventional SPECT were acquired using 99mTc-tetrofosmin as radiotracer in 85 consecutive patients suspect for BC at conventional imaging and clinical examination. Scintigraphic data were related to histology in all cases. BC was proven in 74/85 patients, unifocal in 56/74 cases and multifocal/multicentric in 18/74; 90 carcinomas were ascertained. Benign lesions were found in 12 cases, including one who also had BC in the contralateral breast. DBC planar SM and SPECT were true-positive in 72/74 and in 70/74 BC patients, respectively, and globally detected 96.7% and 92.2% of carcinomas. DBC and SPECT sensitivity were, respectively, 90.3% and 80.6% in <or=10-mm carcinomas and 100% and 98.3% in larger ones; sensitivity values in non-palpable carcinomas were 92.6% and 77.8%, respectively, and 98% for both procedures in palpable ones. DBC planar SM and SPECT correctly assessed multifocality/multicentricity in 91.7% and 83.3% of cases, respectively. Sensitivity differences were not significant. Both procedures showed only a false-positive result. DBC planar SM and SPECT proved highly sensitive and specific in BC detection, representing a useful complementary tool to mammography. However, DBC planar SM showed technical advantages and better clinical performance than SPECT in both subcentrimetric carcinoma detection and multifocal/multicentric disease assessment. Thus, DBC planar SM should be preferred, but SPECT remains a useful alternative when DBC is unavailable.