Chronic lymphatic leukemia (CLL) is a disease with a prognosis that has previously been difficult to assess. In recent years, this problem has largely been overcome by various classifications based on clinical and hematologic findings. This article presents the results of a study designed to show the value of lymphograms in assessing the prognosis. These results show that prognosis is associated with lymph node structure, as assessed by lymphography. Lymphography, as an investigation is superior to scanning or echography, since these give information merely on nodal size. It is proposed that lymphograms should be used for assessing the gravity of the disease and help in the choice of therapy.