Quantitative studies of the influence of the surface composition on the creep of zinc single crystals under constant loads have been carried out. The creep curves of crystals with clean and oxidized surfaces were obtained in air and in acid. It is shown that a continuous layer of oxide strengthens the crystal only at low loads, and that the presence of cracks in this layer allows the metal to creep at its normal rate. These facts support the theory that the oxide film acts to relieve the metal of part of the load. An increase in creep rate is observed when the pure metal surface is treated with dilute mineral acids. The heat liberated by the reaction is considered as a possible explanation of the sudden increase in creep rate when the surface layer of the crystal is removed. The normal creep curves of unoxidized crystals in air may be described by an empirical equation of a new form, and its application to other types of curves obtained is discussed.