Dual task methodology and eye-tracking were used to examine how attention is allocated when walking over terrain of varying complexity. Volunteers completed six test sessions in which they walked for 30 minutes with one of three terrain conditions (no markings, irregular markings, irregular markings). While walking, volunteers also performed a secondary vigilance task with targets placed at either eye level or ground level. Results showed that accuracy on the secondary task declined as terrain complexity increased. Median RT was also significantly faster with no markings than either marking condition. In addition, RTs were faster with the targets at eye level for all marking patterns except the irregular pattern. These data show that walking over varied terrain impacts vigilance.