Anormalities of hemostasis in vivo and in vitro were defined in a prospective study of patients with typhoid fever. In a group of 56 patients with a proven diagnosis of typhoid fever, hemostatic abnormalities were frequently found. In patients with normal clotting tests the fibrinogen level was found to be higher than in normal controls. This finding established a new normal level for patients with typhoid fever. Using this redefined normal level it was found that low fibrinogen was associated with other hemostatic abnormalities. Low fibrinogen levels in patients with typhoid fever are possibly the result of disseminated intravascular coagulation. This process affected 20% of our patients and was often of mild to moderate intensity. Clinically significant bleeding occurred in 18 patients and, in contrast to the results of previously published studies, was found to correlate with clotting abnormalities.