Objective To study relationship between chromosome un-stability and schizophrenia development. Methods Micronucleolus and silver-stained nucleolar organized regions (AgNOR) in the peripheral blood lymphocytes of 120 patients with schizophrenia and 50 healthy persons were tested. Results The frequency of micronucleolus and the number of the AgNOR in schizophrenics were higher than those in the control(P