The staining of HLA class II antigens, the presence of cells positive for interleukin-2 receptors, the proportion of crypt cells in mitosis in the jejunal biopsy specimens, and the dose of coeliac disease marker HLA-DQ genes were studied in 75 healthy family members of coeliac disease patients. Eleven had silent coeliac disease; in the rest the morphology of the jejunum was normal. In the specimens from family members, staining of epithelial cells with HLA-DP and -DR antibodies was more widely distributed and stronger than in those from 19 controls. Interleukin-2 receptor+ cells were seen in the epithelium of all eight specimens from subjects with silent coeliac disease, and also in 24 morphologically normal specimens from family members, but not in the 19 control specimens. The proportion of crypt cells in mitosis was increased only in the specimens from the subjects with silent coeliac disease. The staining intensity of the epithelial cells with HLA-DP and -DR antibodies, the presence of interleukin-2 receptor+ cells and the percentage of crypt cells in mitosis were significantly associated with the number of coeliac disease marker DQB genes. Many family members of patients with coeliac disease have signs of inflammation even in morphologically normal jejunum; these inflammatory changes together with coeliac disease marker DQ genes may point to latent disease in these subjects.