The expression of adhesion molecules in monocytes of patients with recent onset type I diabetes was analysed. Monocytes were identified as CD14-positive cells by flow cytometry. The percentage of monocytes expression LFA-1 alpha, ICAM-1 and HLA-DR was slightly lower in recent onset type I diabetes (n = 13) compared to normal subjects (n = 15) and was significantly decreased after activation of cells with lipopolysaccharide and interferon-gamma for 5-24 hr. Receptor densities on adhesion molecule-positive monocytes and the expression of LFA-1 beta were normal. These data indicate that monocyte trafficking is abnormal in recent onset type 1 diabetes.