We have extended the low temperature magnetic anisotropy measurements on single crystals of zinc containing up to 600 p.p.m. manganese from magnetic fields of 9 to 56 kG. The crystal field splitting parameters determined at low magnetic fields also characterizes the magnetic anisotropy at high magnetic fields. Manganese–manganese interaction effects are observed in the magnetic anisotropy at manganese concentrations greater than 300 p.p.m. Low temperature magnetic anisotropy measurements on single crystals of zinc containing up to 164 p.p.m. chromium are reported and indicate a crystal field splitting of 0.16 K for the chromium ion.