Breast cancer is the third most common cancer in women with about 22% of all cancer incidences arise from breast cancer. Moreover, it is still the leading cause of cancer mortality in women, compare to the other common cancers. Recent several biomarkers have been associated with the disease and these include protein and genetic markers. Due to the absence of both rapid and sensitive diagnostic tools for breast cancer, it cannot be detected in its early stage which is the most crucial point in treatment. Although the disease has available and widely investigated markers, the breast cancer has scarcely been studied with biosensing technology. This book provides theoretical and practical information about electrochemical DNA biosensors for detection of genetic mutations of breast cancer.