Plasma fibrinogen chromatography and other relevant determinations of factors of known importance in thrombus production and dissolution were done serially in 19 hospitalized burned patients. The findings indicate that the coagulation mechanism was chronically activated and that, judging from the observed, sustained elevation of circulating high molecular weight fibrin (ogen) complexes, intravascular clotting was occurring at a pathological, if variable, rate. In patients older than 50 years of age, a relatively impaired thrombolytic response was also found; the latter finding is of special interest, as it provides biochemical substantiation for the well-recognized clinical proclivity of elderly burn patients to thromboembolic complications.