The objective of this study was to investigate the efficacy and safety of desmopressin (1-desamino-8-D-arginine vasopressin) compared with placebo in the reduction of menstrual blood loss in women with menorrhagia and prolonged bleeding time, but without common coagulation factor deficiencies. We performed a randomized, double-blind, cross-over study using 300 microg desmopressin nasal inhalation or placebo treatment in one of the two first treatment cycles. Desmopressin was given only for the 2 days during which the bleeding had been at a maximum in the previous baseline cycle. A third open cycle involved combined treatment with desmopressin and tranexamic acid during the 2 days for all patients. Menstrual blood loss during the treatment periods was compared with blood loss during placebo-treated periods using objective measurement. A significant reduction of menstrual blood loss was found in the cycles treated with combined desmopressin and tranexamic acid compared with placebo. When analyzing the blood loss during the two treatment days, there was a significant reduction in blood loss for the 2 days with desmopressin alone versus placebo. The treatment was well tolerated and no serious adverse events were recorded. In conclusion, we find that nasal desmopressin is a possible complement for the medical treatment of menorrhagia.