We present a velocity field of the planetary nebula A78 based on three Fabry Pérot Hα (10A) interferograms taken with a focal reducer attached to the 2.1 m reflector of the Observatorio Astronómico Nacional at San Pedro Mártir, Mexico. We have used a single-stage Varo image intensifier and two different étalons with interorder separations of 283 km s−1 (2 interf.) and 100 km s−1 (1 interf.). The scale of the original photographs is 49 arcsec mm−1. Our data have yielded radial velocities in the Hα line at 110 points on the face of A78; the velocity field is far from being smooth. The rings are wide around the central hole, and a few show definite splittings; from these splittings we have estimated an overall expansion velocity of 27 km s−1. The average systemic velocity is found to be around −3 km s−1.