Magnetization measurements have been carried out on a single crystal of DyA103 at temperatures (T) between 1.2 and 300 K. Consistent with earlier studies, the material was found to be antiferromagnetic below T&=3.5'K. Metamagnetic transitions were observed for fields (H -14. 5 kOe) applied in the (001) plane of the orthorhombic unit cell at T = (1.45+ 0. 005) 'K.The critical fields were in the range 5. 9-11.3 kOe, depending on the angle 0 between H and the a axis of the crystal. A two-step transition was observed in fields (H~60 kOe) applied along the [110)direction at T=1.2'K. The critical fields in this case were (6.5+0.3) and (24. 3+1.2) kOe for the two steps in the magnetization'curve.The data showed that any of the four Inagnetic sublattices in DyA103 may be reversed selectively by applying H in an appropriate direction. However, in a range of angles near the b axis (8~73'), the favored transition involves a reversal of the magnetization simultaneously on two of the sublattices. Expressions for critical fields were derived theoretically and fitted to the data, yielding estimates of the internal fields in DyA103. These estimates were compared to values derived earlier in published optical studies of DyA103, and to analogous quantities in the isomorphous compounds GdA103 and TbA103.