Cyclotron resonance of holes orbiting in the a-b plane of an anthracene crystal has been observed. This represents the first time that this phenomenon has been observed in a molecular crystal. From these experiments, the hole effective mass is determined to be 11me where me is the free-electron mass. The hole scattering time at 2°K was measured in two different crystals and found to be ∼7×10-11 sec in one crystal and 4 ×10-10 sec in the other. © 1974 The American Physical Society.