The optimal technique for sentinel lymph node biopsy (SLNB) is still debated. SLNB with peritumoral injection of Patent blue dye was performed in 129 clinically T1-T2 and N0 breast cancers in 127 patients (group A); it was later replaced by combined dye and radiocolloid-guided SLNB preceded by lymphoscintigraphy in 72 breast cancer patients (group B). This study compares these two methods. All patients underwent completion axillary dissection. Means of 1.4 and 1.3 SLNs were identified in groups A and B, respectively. The mean number of non-SLNs for the whole series was 14.9 (range 5-42). The first 53 cases of lymphatic mapping (dye only) comprised the institutional learning period during which the identification rate of at least 1 SLN in 30 consecutive attempts reached 90%. The identification rate for the subsequent 76 group A patients was 92%. The accuracy rate of SLNBs for overall axillary nodal status prediction and the false-negative rate for group A patients (after excluding the learning-phase cases) were 93% and 10%, respectively. All 72 group B cases had at least one SLN identified, and only one false-negative case occurred in this group (accuracy and false-negative rates of 99% and 3%, respectively). Both the dye-only and the combined SLNB methods are suitable for SLN identification, but the latter works better and results in higher accuracy, a higher negative predictive value, and a lower false-negative rate. It is therefore the method of choice.