A system and method for detecting brain concussion includes detecting and measuring of acceleration at one or more points on a subjects head. Sensors, which can be accelerometers placed against the head, detect and measure natural motions of the patients head due to blood flow in the brain and resultant movement of tissue in the brain. The acceleration data are then analyzed, including as to frequency of motions of the skull at the subject location in a frequency range of about 1 to 20 Hz. An observation is then made, as compared with data corresponding to non-concussion, of a change in frequency response pattern exhibited when accelerations are plotted as a function of time or frequency, to identify probable concussion if the frequency response pattern indicates concussion. Preferably the observation and comparison are made by a computer using an algorithm.