This is an interesting exposition of an uncommon but serious disease, and is based chiefly on data derived from twenty-five personally observed cases of cavernous sinus thrombosis. The author stresses the importance of differentiating clinically between sudden and gradual obliteration of the sinus, and discusses the various routes by which the latter may be invaded. Embryology of the sinus, as well as its surgical anatomy and pathology, are considered. Ligation of the internal carotid artery, which, by its pulsations disturbs the thrombosed venous channel, is strongly advocated. The author has seen few untoward symptoms following this apparently radical procedure. Attention is paid to serum and vaccine therapy, and a complete general bibliography is given.