Circulating tumor cells (CTCs) are malignant cells found in the peripheral blood of patients with solid tumors.Although this phenomenon was recognized more than a century ago, the very low number of CTCs relative to other circulating cells in the blood makes their detection difficult.Technological development in the past decade has made it possible to detect and characterize these cells.Due to the rarity of CTCs, most of these techniques use some sort of enrichment method followed by a detection step.The presence of CTCs has been increasingly used as a prognostic marker and a tool to monitor treatment response in cancer patients.This presentation provides a brief review of the different techniques used for the detection of CTCs in breast cancer patients and its clinical significance.