Most of the prominent blood vessels on the back of the hand are caused by physiological reasons, but it may also be caused by phlebitis and other diseases. 1. Physiological phenomenon: People who are thin, with little subcutaneous fat and weak skin, as well as those who often exercise and engage in heavy physical labor, are prone to have prominent veins. In addition, the veins of the elderly gradually dilate, and the blood vessels on the back of the hand will also appear prominent. Clinically, most of the prominent blood vessels on the back of the hands are normal physiological phenomena. 2. Phlebitis: For example, thrombophlebitis may cause abnormal function of the venous valves, which may result in abnormal local blood flow and cause prominent blood vessels on the back of the hands. If the blood vessels on the back of the hand are prominent, excluding physiological phenomenon, or if the body itself has other chronic diseases, you should go to the hospital for examination in time and follow the doctor’s instructions for treatment.