Abstract: In pharmaceutics for mucosal administration containing pharmacologically active peptides or proteins and tolmetin or salts thereof exhibited very excellent effect as mucosal absorption enhancers.Furthermore, when the pharmaceutics for mucosal administration are for rectal administration, the suppository in which at least either the active ingredient, peptide or protein, or the mucosal absorption enhancer is converted to a complex with a high molecular compound dissolving in water at pH 5 or higher and together uniformly dispersed in a fatty suppository base exhibited markedly improved rectal absorbability compared with that of conventional pharmaceutics for rectal administration and at the same time increased stability of the peptide or protein which is the active ingredient.