Peripheral blood leucocytes from chronic myeloid leukaemia patients in remission were tested for inhibition of migration in presence of solubilized membrane antigens from leukaemic cells in 15 cases. Eight out of 9 autochthonous combinations (88-8%) and 35/49 allogenic combinations (71-4%) showed inhibition of migration. Antigens prepared from relapse leukaemic cell samples in 4 cases showed inhibition of migration of autochthonous as well as allogeneic remission leucocytes. The same batch of CML antigens inhibited migration of normal leucocytes at the level of 22-2%. The difference between inhibition of migration shown by remission leucocytes and normal leucocytes in presence of CML antigens was statistically significant. Solubilized antigens, similarly prepared from normal leucocytes, showed inhibition of migration of remission leucocytes to the extent of 15% only. The difference between the reactivity of CML remission leucocytes to normal and CML antigens was also statistically significant. No enhancement of migration of remission leucocytes was seen with CML antigens