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Aims and Objectives: Currently the triple technique (including preoperative SLN imaging using SPECT CT after radioactive colloid injection; intraoperative injection of blue dye; and intraoperative usage of hand held gamma probe) has been demonstrated to be most accurate for the identification of Sentinel lymph node (SLN). However the availability of nuclear medicine department for SLN imaging is one of the major barriers in the diffusion of SLNB technology. The purpose of this study was to investigate whether the SLN detection rate using the intraoperative dual mapping (radioactive colloid + methylene blue dye) technique is comparable to the triple technique in a prospective trial. Methods: This prospective trial was started in the department of breast and gynecology oncology in collaboration with department of nuclear medicine at Amrita Institute of Medical Sciences, Kochi, Kerala in May 2017. Intraoperative dual SLN mapping technique consisted of subareolar injection of technetium 99m- labelled filtered sulphur colloid (15-37 MBq) and 3ml of 1% isosulphan blue dye just after anaesthetic induction followed by locating and dissecting the SLN using hand held gamma probe and blue dye. Triple technique consisted of subareolar injection of radioactive colloid followed by SPECT CT preoperatively; subareolar injection of blue dye intraoperatively; locating and dissection of SLN using gamma probe and blue dye. SLN biopsies (SLNBs) or complete axillary dissections were carried out, and SLNs identified during these procedures were classified as containing both blue dye and radioactivity ("blue-hot" nodes), radioactivity alone ("hot-only" nodes), or blue dye alone ("blue-only" nodes). Cases were categorized and tabulated based on the presence or absence of these three types of SLNs. Endpoint measured was the overall SLN detection rates and were compared between the two techniques. Results: Out of total 375 SLNBs done, 203 were done using triple technique and 41 using dual technique. SLN detection rates with intraoperative dual mapping technique was 100%, while that of triple technique of SLN identification was 97.6% (p = 0.216). We looked into the SLN detection rate of the individual procedures of the two techniques (triple versus dual technique): SLN detection rate of preoperative imaging using SPECT CT after radioactive dye injection was 100% in triple technique (procedure not performed in dual technique); SLN detection rate of intraoperative injection of blue dye ("blue" node) was 76% in both the techniques; SLN detection rate of "hot" nodes with the gamma probe was 94.5% in triple and 99% in dual technique; and the SLN detection rate of "hot and blue" nodes was 96.7% in triple and 100% in dual technique. Using either technique the SLN location was in axilla in 100% of cases. In 100% cases the surgical approach for SLN biopsy remained same. Conclusion: SLN detection rate of intraoperative dual technique was equivalent to the SLN detection rate of triple technique. Thereby in low resource settings where SPECT CT imaging is not possible in vicinity, the sentinel lymph node biopsy can still be performed by procuring the radioactive colloid (from outside centre) and blue dye and the hand held gamma probe. [ABSTRACT FROM AUTHOR]