UML-491,* 1-methyl-D-lysergic acid butanolamide bimaleate, a derivative of lysergic acid, is being extensively investigated as regards its apparent although limited effectiveness in prevention of vascular headache.1,2,3 It is known to have an antiserotonin and an antiedema action in laboratory animals.4,5,6 It is also known not to have a direct or immediate vasoconstrictor action.8,9 To establish whether or not such antiedema effects of this agent are specific for serotonin, and whether the agent also possesses a nonspecific anti-inflammatory effect in man, a series of observations using manganese butyrate as a noxious agent to induce sterile inflammation were undertaken. Furthermore, observations concerning its central action and its indirect effect on peripheral vascular structures were noted. Anti Inflammatory Action of UML-491 in Man The method of Lovell, Goodman, Hudson, Armitage, and Pickering7 was applied in order to define whether or not UML-491 has an anti-inflammatory action in human subjects