1. The combination of a wire-mesh support with the roller-tube technique is described as a procedure for the culture of human jejunal mucosa in vitro. 2. The technique has been applied to fragments (approximately 10 mg) of jejunal biopsies from both normal subjects and patients with coeliac disease. 3. The cultured tissue has been shown by radioautography to incorporate [ 3 H]leucine into proteins of the villus epithelial cells and [ 3 H]thymidine into nucleic acid, predominantly by the enterobiasis. 4. Although the tissue protein and DNA contents fall during culture, it was found that the combined tissue and medium DNA content remained constant during culture and may be used as a reference for enzyme and biochemical studies on cultured intestinal biopsies.