Abstract: Method and system for navigated medical procedures includes a transmitter array having at least three ultrasound transmitters and at least one optical transmitter, and a receiver array having at least three ultrasound receivers and at least one optical receiver. In each transmission, the optical transmitter and only one ultrasound transmitter transmit signals. Distance measurements between each ultrasound transmitter and each ultrasound receiver are calculated based on time delays between reception of signals transmitted in each transmission and a speed of sound. A three-dimensional location of a transmitter relative to a receiver, or vice versa, is determined from at least three calculated distance measurements. Placement of the transmitter or receiver array on a surgical tool, a medical implant or instrument, or a part or point in or on a patient's body, or other object used in the medical procedure, enables the three-dimensional location thereof to be viewed on a display.