A head holder for stereotaxic electrode placement in the neonatal rat is described. The neonatal head is held in a fixed and reproducible position by means of a mouth bar and a recurved needle hooked into the foramen magnum. With the aid of this instrument, a stereotaxic atlas for the 3-day-old rat has been prepared. The head holder has been used for rats up to 10 days of age and permits electrode placement in the neonatal rat in a manner essentially analogous in ease and precision to that of stereotaxic methods for the adult animal.