Capping with concanavalin A (ConA) and monoclonal anti-HLA-ABC backbone was studied in childhood acute lymphoblastic leukemia (ALL). Capping with ConA and HLA gave quite different results, both in common ALL and T-ALL. With ConA most cases capped poorly, comparable to results described in chronic lymphatic leukemia and lymphoma, but in several cases capping was comparable to that of normal lymphocytes. In HLA capping T-ALL cells capped better than common ALL cells. HLA capping of T-ALL cells is comparable to that of normal lymphocytes. HLA capping results in handmirror cell formation giving support to the hypothesis that capping and motility are associated events.