To determine whether monocular patching influences the performance of a patient with primarily sensory-attentional bias on the line bisection task, we present a case study of a 49-year-old woman who had right cortical infarction affecting temporal, parietal, and occipital regions. She had primarily sensory-attentional bias when performing the line bisection task on a video apparatus. In hospital, she was tested with monocular eye patching of the left or the right eye or unpatched. Paradoxically, the right-eye patching significantly worsened and the left patch significantly improved performance. The eye may have some input to the ipsilateral as well as the contralateral superior colliculus. Alternatively, the patch-a novel tactile stimulus-may induce orienting to its side via noncollicular mechanisms. When using a monocular patch for any reason, clinicians should be aware that increased spatial bias may occur. © 2001 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.