In two experiments, we investigated the impact of feature-based attention on observers' awareness of object appearance. Participants were shown a sequence of two displays, each containing eight objects (rectangles), and were asked to detect changes in the orientation of a cued rectangle. A set of baseline trials preceded probe trials in which half of the rectangles in each display were unexpectedly distorted by 70 %. Participants in both Experiment 1 (100-ms display duration) and Experiment 2 (100- and 400-ms display durations) were unaware of these modifications in the task-irrelevant feature (texture), even when they were asked to select the viewed object in a forced choice procedure. A control experiment showed that participants could identify the physical distortion when they were made aware of its presence. The results demonstrate that feature-based attention moderates the appearance of objects, even when those objects are fully expected and fully attended, implying a distinct form of unawareness that we term feature-based inattentional blindness.