Since its first description by Cruveilhier1 in 1829 melanotic pigmentation of the large intestine had been only occasionally observed. From his autopsy observations made in 1858, Virchow2 applied the term melanosis coli to the condition. It was 1911 before the first clinical report by Pick3 appeared on the recognition sigmoidoscopically of this discoloration of the intestine. While melanosis coli is not a rare condition it is practically unknown to the average physician. When observed sigmoidoscopically it usually has been passed by or referred to casually as "brown bowel" or by some other descriptive term and its clinical significance overlooked. The latter circumstance has prompted us to present this paper. GROSS APPEARANCE THROUGH THE SIGMOIDOSCOPE The mucosal pigmentation in melanosis coli varies widely in different persons. It is usually some shade of brown ranging from a light, almost gray, tone to a deep, dark hue almost inky black.