This article examines the effect of the spatial resolution of digital elevation models (DEMs) on slope and aspect data. After a review of computing methods for slope and aspect and such factors as DEM resolution, topographic complexity, and quality of DEM data, the article presents two experiments using DEMs from 8 to 80 m intervals. Results of the experiments show that the accuracy of slope and aspect data, as well as the mean and standard deviation of slope values, decrease with lower DEM resolutions. Comparison of slope and aspect maps generated from different resolutions reveals that slope differences concentrate in areas of steep slopes, whereas aspect differences are in generally flat areas with minor landform features. Slope differences can be explained statistically by relative relief, and aspect differences by relative relief and standard deviation of elevation.