ZnO crystal whiskers were prepared via a simple thermal evaporation of a mixture of ZnS and Fe(NO3)(3). The growth process was carried out in an alumina tube at 1300 degreesC using Ar mixed with 5% H-2 as the carrier gas. The ZnO whiskers obtained had diameters ranging from 200 to 500 urn and lengths up to several hundreds of micrometers. The photoluminescence spectrum of as-grown ZnO whiskers was studied. The influences of reaction temperature, time, and carrier gases on the formation of the whiskers were investigated. A preliminary growth mechanism of the ZnO crystal whiskers was proposed.