To determine if the susceptibility of patients with lymphoma, particularly Hodgkin''s lymphoma, is related to an abnormality in leukocyte function, the serum, neutrophils and monocytes from 29 patients with all stages of untreated Hodgkin''s disease were studied simultaneously with a group of normal subjects. The patients'' neutrophils and serum functioned normally in the killing of Escherichia coli, Staphylococcus aureus, Listeria monocytogenes and Salmonella typhimurium. The killing of E. coli and Listeria by their monocytes was equal to that of monocytes from the control subjects. A significantly greater number of Salmonella and Listeria were recovered from monocyte-derived macrophages from Hodgkin''s patients than control subjects after 1.5 h of challenge with bacteria. This suggests that the macrophages from Hodgkin''s patients may be more avidly phagocytic than normal.