White-tailed deer (Odocoileus virginianus) activity levels were estimated by track counts on 3 study sites in the Cross Timbers region of Oklahoma during 1978-79. An activity index (number of tracks/ day) was developed from repetitive readings of 100 track plots (1 X 3 m) per site. Significant differences (P < 0.05) in monthly activity levels were found. Within-month and between-month variability was influenced by land-use patterns, ambient temperature shifts, changes in food resource availability, and deer behavior patterns. A seasonal bimodal pattern was observed, with peaks during late spring and falI-early winter, while lowered activity was observed during early spring and summer.