Although many investigators have been actively engaged in experimental work with the virus of lymphocytic choriomeningitis or with infected animals, comparatively few have contracted the disease or, of those tested, few have developed neutralizing antibodies in their serum.1Lépine and Sautter2were first to report a laboratory infection of lymphocytic choriomeningitis. Virus was isolated from their patient's blood and urine, and complement fixing antibodies were demonstrated in the patient's serum during convalescence. The serums of 2 persons who had worked for two years with the same virus strain and infected animals failed to fix complement. Lépine and Sautter mention no attempt to detect virus neutralizing substances in their patient's serum. They believe that their patient became infected nine days before onset of symptoms by fragments of contaminated glass that were accidentally splattered into her eye during the process of grinding infected guinea pig tissues with powdered glass. More