Interrelationships among six patient characteristics recorded upon entry into the trial were analyzed for 67 patients with lepromatous and near-lepromatous leprosy admitted into two chemotherapy trials. Sex was found to be significantly associated with age and with the histopathologic classification; disproportionately large numbers of older patients and of patients classified as borderline-lepromatous (BL) were males. Classifications of the disease process by clinical and histopathologic criteria were closely associated, but many patients classified BL on histopathological grounds were classified fully lepromatous by the clinical criteria. Measurements of the number of Mycobacterium leprae in the patients made by three methods were also significantly correlated. No significant correlations were found between either classification of the disease process on the one hand, and any of the measurements of the numbers of organisms on the other.