Several systems and methods for locating blood vessels are described in the present disclosure. One of the implementations of a blood vessel locating system comprises an image capture device and processing circuitry. The image capture device is configured to capture a first image of a region of the skin of a subject when the region is illuminated by a first light and to capture a second image of the region of the skin when the region is illuminated by a second light. The processing circuitry is configured to calculate the difference between the first image and the second image to obtain a differential image. The processing circuitry is further configured to enhance the differential image to obtain an enhanced image of blood vessels located under the surface of the skin of the subject.