Subdural injections of relatively large quantities of lipiodol into rabbits give rise to acute leptomeningitis, evidenced histologically by an extensive infiltration of cells (mainly leucocytes). It subsides in 2-3 weeks. In 1 case out of 7 it resulted in death. After the period mentioned above no histological changes remain, in spite ot remaining large quantities of lipiodol. After intralumbar injection of lipiodol (5-10 cc.) in man, acute leptomeningitis develops with marked increase of cells in the lumbar fluid (exclusively lymphocytes). The meningeal symptoms subsided within 2 weeks after the injection.