Primate cones maximally sensitive to short wavelength light (blue cones) have been previously identified by using indirect methods. We stained 7 wholemounted human retinas obtained from 6 female donors, using an affinity purified antibody to a 19 amino acid peptide sequence at the N‐terminus of blue opsin (Lerea et al., '89: Neuron 3:367–376), standard PAP immunocytochemistry, and controls. Cones were counted where all outer segments could be traced to inner segments and were measured where cells were well aligned vertically. We find that: (1) 7% of cones within 4 mm of the foveal center are labeled by antiblue opsin; (2) compared to neighboring red/green cones, blue cone inner segments are 10% taller, have a larger cross‐sectional diameter near the junction with the outer segment, and a smaller diameter near the external limiting membrane, resulting in a more cylindrical shape, (3) foveal blue cones are sparse, irregularly spaced, and missing in a zone about 100 μm (0.35°) in diameter near the site of peak cone density, (4) the highest densities of blue cones (> 2,000 cells/mm2) are found in a ring at 0.1–0.3 mm eccentricity, and (5) the shortest distances between neighboring cones are between blue and red/green cones, and the blue and red/green mosaics are statistically independent. These findings are consistent with psychophysical reports of foveal tritanopia and maximum sensitivity to blue light at 1° eccentricity. Blue cone spacing may limit resolution of the blue channel out to 20–30° eccentricity. The blue and red/green mosaics appear to be formed by separate processes. Copyright © 1991 Wiley‐Liss, Inc.