Diurnal and seasonal patterns of activity and habitat associations of white-tailed deer (Odocoileus virginianus) were assessed in a mosaic of grassland and woodland habitats on the Konza Prairie Biological Station, Kansas. We recorded deer seen during daylight hours in summer, autumn and winter periods from June 1997 through February 1998. Overall, diurnal activity increased from summer to winter and was largely crepuscular (i.e., early morning and late evening). Deer were observed primarily in lower uplands during summer and winter, and in lowlands during autumn. At a coarse scale (6.25 ha), white-tailed deer selected areas that had woody vegetation and avoided those that were dominated by grassy vegetation. In contrast, at a fine scale, groups of deer most often were observed foraging in the immediate vicinity of grassland vegetation, rather than in or by woody vegetation.