This study describes a role of platelet-activating factor (PAF) as a potential inducer of inflammation in infection with Borrelia burgdorferi. Two approaches were taken. The first involved the use of a PAF antagonist to show the lack of an inflammatory response in skin lesions. The second was to show that the PAF antagonist reduced platelet aggregation when the spirochetes were incubated with polymorphonuclear leukocytes.