An aseptic cap for containers with evidence of first opening includes a protective cover positioned on a pouring element and produced as a single piece, which has an upper and a lower part connected by frangible bridges facing edges of the upper and the lower parts of the cover, and by a hinge arrangement. The pouring element includes a cylindrical element formed by two sections having different diameters separated by a step defined by a radial annular extension, which protrudes from the lower cylindrical part of the cover and is at least partially inserted in the upper part of the cover. The upper part of the cover has, in its interior, an appendix or flap which extends to rest above the annular extension, to become folded when the cap is mounted, and which is arranged straight downwardly to be abutted above the annular extension after the first opening.