Summary. Lewit and Sereghy (1975) have expressed some doubts about the existence of the dorsal plica mediana and its relation to the median translucency regularly seen on peridurographic pictures made in the PA projection. The present paper reports the demonstration of the dorsal plica mediana in fresh anatomical preparations under conditions lowering the intradural pressure, and the relation of the plica to the peridurographical median translucency, shown on the basis of the injection into the lumbar peridural space of a gelatine solution containing India ink.