Menadiol is one of the forms of vitamin K4. Chemically, it is closely related to menadione. Oral menadiol appears to be an effectiv ealternative to intravenous phytomenadione in the correction of coagulopathies associated with obstructiveliver disease. This simplifies the care of patients with deranged clotting times requiring cholangeopancrea-tography, particularly those to be managed as out-patients. Menadiol should receive clinical testing as a chemosensitizing agent in human lymphatic neoplasms (HLN). This effect occurred at a concentration (2.0 micrograms/ml; 4.7 microM) of menadiol which is probably clinically achievable and which did not deplete intracellular glutathione.