In the article “Independent Projection Streams from Macaque Striate Cortex to the Second Visual Area and Middle Temporal Area,” by Lawrence C. Sincich and Jonathan C. Horton, which appeared on pages 5684–5692 of the July 2, 2003 issue, the authors discovered an error in the calculation of cell body size. On re-analysis, the cell body areas are larger by a factor of 10.45, for all populations. Thus, the median cell areas reported on p. 5687 should be 78 μm2 for the cells projecting from V1 to V2, 203 μm2 for V1 to MT projecting cells, and 161 μm2 for the manifold V1 cells that project to V2 and MT. Values on the abscissa of Figure 5i should be multiplied by this scaling factor. None of the conclusions in the paper are altered.