A procedure using data from tests with a sufficient number of observation wells is presented herein for determining the transmissivity in any direction and the storativity of a homogeneous anisotropic nonleaky aquifer. The procedure assumes that the distribution of the observation wells is such that the elliptical shape of an equal drawdown curve during pumping or of an equal residual drawdown curve during recovery is so clearly delineated as to make possible a graphical determination of the major and minor axes of these ellipses. The method is developed primarily for analyzing recovery data from such tests. It can be used, however, for analyzing data from the pumping period. (Key words: Groundwater; hydraulics; wells)