The reaction of silyl bromide with the products of the reactions of amines with lithium tetrahydridoaluminate has been studied. N.m.r. parameters of a large number of N-silyl compounds are reported and their significance is discussed. The parameters enable predictions to be made concerning Si–N bond lengths in a number of cases. The silylamines studied include the new species, N-silylpyrrole, N-silylphthalimide, N-silylsuccinimide, and N-silylazetidine. Some reactions of silylamines are described, including insertion reactions of carbon dioxide, carbon disulphide, and carbonyl sulphide into the Si–N bond of silyl derivatives of some secondary amines. The products with carbonyl sulphide show restricted rotation about the R2N–C bond.