Collagenous sprue is a severe malabsorptive disorder, histologically characterized by small intestinal villous and crypt atrophy, and a subepithelial collagen deposit, thicker than 12 µm, that entraps lamina propria cellular elements. Collagenous sprue is a rare disease entity, with only about 60 sporadic cases reported worldwide since it was first described in 1947. Its exact etiology is still under investigation, and its relationship with classic celiac disease and other refractory, spruelike intestinal disorders remains controversial. Two larger-scale studies, in 2009, brought new insights into this elusive, yet emerging, topic. Here, we present a review of the literature on the possible etiology of collagenous sprue, its proposed links to classic celiac disease and to refractory sprue, and its clinical, biochemical, histologic, and molecular features. To our knowledge, all case reports on collagenous sprue in the medical literature to date are summarized.