Replacement therapy with blood products has long been the only available therapeutic option for patients with bleeding disorders. Plasma-derived cryoprecipitate and factor (F) VIII concentrates, which have been used for hemophilia A patients, involve the risk of transmitting blood-borne diseases. Both plasma-derived and recombinant FVIII concentrates are expensive, and there is a global shortage. The synthetic vasopressin analogue desmopressin acetate (1-deamino-[8-D-arginine]-vasopressin, DDAVP) increases plasma concentrations of coagulation FVIII and von Willebrand factor (vWF) two fold to six fold through endogenous release. The drug is an attractive therapeutic alternative because it carries no risk of transmission of infectious diseases. Desmopressin is today a widely used hemostatic agent not only in patients with mild hemophilia A or von Willebrand disease (vWD) but also in those with congenital or acquired platelet dysfunction. There is a long clinical experience with the drug because it has been used for prevention of bleedings in connection with invasive procedures and for treatment of bleedings since the mid-1970s. Not all hemophilia A patients can be treated. The clinical usefulness depends on the postdesmopressin plasma concentration of FVIII, which in turn depends on the patient's basal FVIII level. Therefore, a test dose is recommended in candidate patients. In general, only the mildest hemophilia A patients respond sufficiently. Optimal hemostatic effect is achieved with a dosage of 0.3 microg/kg given intravenously. An intranasal desmopressin spray is suitable for the home treatment.