An aseptic cap for containers with evidence of first opening, the cap comprising a protective cover positioned on a pouring element, wherein: - said protective cover is produced in a single piece and consists of an upper part and a lower part connected by a series of frangible bridges, produced in correspondence with facing edges of the upper part and the lower part of the cover, and through a hinge arrangement, - said pouring element comprises a cylindrical element formed by two sections having different diameters (21,22) separated by a step defined by an annular extension positioned on a plane perpendicular to an axis X of the two sections (21,22) of the cylindrical element in a radial direction in the cylindrical element, - wherein said annular extension of said pouring element is positioned protruding from the lower cylindrical part of the cover and is at least partially inserted in the upper part of the cover so that said series of frangible bridges is arranged externally with respect to one of said sections (21,22) of the cylindrical element of the pouring element which has a larger diameter and is inserted in said cylindrical lower part of the cover, and characterised in that - the upper part of the cover provides, in its interior, at least one appendix or flap which extends to rest above said annular extension, folded, when the cap is mounted and ready for use for application on a container, and which is arranged straight downwardly to be abutted above said annular extension when the first opening of the upper part of the cover has been effected with respect to the lower part of the cover and the pouring element, and when an attempt has been made to close the cover on the pouring element. - said protective cover is produced in a single piece and consists of an upper part and a lower part connected by a series of frangible bridges, produced in correspondence with facing edges of the upper part and the lower part of the cover, and through a hinge arrangement, - said pouring element comprises a cylindrical element formed by two sections having different diameters (21,22) separated by a step defined by an annular extension positioned on a plane perpendicular to an axis X of the two sections (21,22) of the cylindrical element in a radial direction in the cylindrical element, - wherein said annular extension of said pouring element is positioned protruding from the lower cylindrical part of the cover and is at least partially inserted in the upper part of the cover so that said series of frangible bridges is arranged externally with respect to one of said sections (21,22) of the cylindrical element of the pouring element which has a larger diameter and is inserted in said cylindrical lower part of the cover, and characterised in that - the upper part of the cover provides, in its interior, at least one appendix or flap which extends to rest above said annular extension, folded, when the cap is mounted and ready for use for application on a container, and which is arranged straight downwardly to be abutted above said annular extension when the first opening of the upper part of the cover has been effected with respect to the lower part of the cover and the pouring element, and when an attempt has been made to close the cover on the pouring element.