Acridine orange, a rapid and technically simple fluorochromic stain of nucleic acids, was applied to sections of 18 specimens of resected distal colon in infants with Hirschsprung's disease. Neurons were readily identified in the submucosal and myenteric plexuses of normal ganglionic segments because of their intense orange cytoplasmic fluorescence of ribonucleic acid (RNA) that contrasted with the pale green of the smooth muscle and connective tissue. This technic, which may be applied to both frozen and paraffin-embedded sections, is a useful adjunct in the confirmation of aganglionic segments of bowel wall.