Serum albumin levels were measured by electrophoresis in 552 evaluable patients with Hodgkin's disease. Determinations were made on all patients at onset, on 224 after induction therapy and on 78 in relapse after remissions of variable length. At onset a discrete hypoalbuminemia was evident, inversely related to stage and more marked in symptomatic cases and elder patients. Little or no differences in albumin levels were found with relation to histologic subtypes, sex and presence of weight loss or hepatic damage. Posttherapeutic normalization of serum albumin occurred only after achievement of complete remission and failed after partial remission, while a new clear decrease became evident in relapse. On the basis of 799 albumin measurements during active disease and in remission, the albumin/alpha 2-globulin ratio demonstrated a clear and useful clinical advantage over either albumin or alpha 2-globulin fractions alone as indicator of active disease and relapse. If defective synthesis is the most accepted mechanism for hypoalbuminemia in Hodgkin's disease, these results suggest a casual factor somehow related to the tumoral mass.