Complex immunologic alterations occur following thermal injury. To further delineate the intricacies of the immune response, a longitudinal profile of immunologic parameters was investigated in burned patients with specific reference to clinical criteria (resuscitation, plasma exchange, surgical excisions, sepsis). During a 17-month period, 26 adult patients with a mean age of 32.6 years and a mean burn size of 45.6% TBSA were evaluated with serial (twice weekly) assays of immunocompetence. The immunologic variables monitored included complement components, fibronectin, immunoglobulins, acute-phase reactants, serum proteins, catecholamines, and the mixed lymphocyte reaction. Resuscitation from burn shock and clinical sepsis were associated with a wide array of serologic abnormalities and lymphocyte suppression. Plasma exchange and surgical excision and grafting procedures were also characterized by multiple serologic changes and improvement in lymphocyte function. No specific serologic parameter correlated well with cellular function; however, patterns of humoral alterations were consistently present and may represent a combined effect.