The AA. have compared a new medium for the selective isolation of Neisseria gonorrhoeae (the Modified New York City - M.N.Y.C.) with the classic Thayer-Martin medium (T.U.). The study has been carried out on 490 patients of the Center for Venereal Diseases of the University of Milan. Neisseria gonorrhoeae has been isolated in 31% of cases on M.N.Y.C. and in 27% on T.M. On the M.N.Y.C. medium the growth has been much more rapid and luxuriant. No culture has ever been found to be positive on T.M. and negative on M.N.Y.C. On the M.N.Y.C. medium the bacterial contamination and the growth of yeasts was noted to be less frequent, in particular on cultures from female patients.