Measuring Retinotopy in human subjects has become a standard procedure of contemporary fMRI studies on visual cortex. Since the sheet of gray matter at the occipital pole is roughly 2-3mm thick, a typical fMRI voxel of 3 x 3 x 3 mm will contain signal from a mixture of gray matter, white matter or cerebrospinal liquid. Many voxels will sample from the two opposite sides of a sulcus, thereby containing signal from two locations close in 3D space, but distant locations on the cortical surface (partial voluming). Higher resolution protocols are usually avoided because they are expected to entail a worse signal to noise ratio. Methods: We measured retinotopy with a resolution of 1.2x1.2x1.2 mm voxel size (29 slices; EPI matrix size of 176x176; FOV 209mm; FLIP angle 90deg; TE 36ms; repetition time 3s, SENSE factor 2.0) with a 3T Philips Achieva X Series and an 8 channel head coil. We also collected T1-weighted 3D structural scans at 0.75mm resolution and carefully segmented them for accurate gray-white segmentation. We used the Stanford Vista Tools for flattening and analyzing these data. Results: Use of high resolution EPI sequences resulted in a substantial resolution of the gyral structure, providing detailed mutual information for precise alignment between the functional and structural data. We resolve different mean luminance values for gray (raw luminance value of an example voxel: mean 82 std of 2.6) and neighboring white mater voxels (64 std 3.1) in our functional (T2 weighted) scans. Typical BOLD modulation was in the order of 8-12% (9%-14% peak to peak) in single voxels. Figure 1 shows the response (averaged across five runs) of two single voxels 1.2 mm apart in 3D space, but responding to different eccentricities of the cyclic retinotopic stimuli (color coding on the right). Conclusion: We find that BOLD modulation for retinotopy stimuli within voxels increases with resolution, while reducing confounding crosstalk of measured signal across sulci. This is a necessary prerequisite for detailed analysis of flat maps of visual cortex.