A flip top cap for containers with evidence of first opening, the cap comprising a cover part and a pourer part coupled together by means of a hinge arrangement , wherein: - said cover part is rotatable around said hinge arrangement to be brought from a closed position on said pourer part to an open and separate position with respect to said pourer part ; - engagement means are provided when said cover part is rotated into said closed position on said pourer part ; wherein - said cover part and said pourer part are produced in a single piece by moulding; - said engagement means are of the breakable type (28,30;228,230) and are arranged partly on said cover part and partly on said pourer part and remain integral with at least one of said parts when they are broken at the first opening, wherein said pourer part comprises an essentially cylindrical section (16,17 and 18) and an actual pouring section , having a reduced diameter with respect to the cylindrical section, connected by a flat annular element or step , extending radially to connect said two portions (16,17 and 18;26), characterized in that on said flat element or step of the pourer part , there is an inverted L-shaped flap element , which extends into a leg facing downwards, wherein said leg in a closed position of said cap is inserted between the cover part and the pourer part so as allow a complete closure between the same, and after a first opening, said leg facing downwards with respect to the axis of the cap is arranged and engages on an external part of a mouth of the container (C) which pushes it towards the outside and opposes their complete closure in contact between the cover part and the pourer part . - said cover part is rotatable around said hinge arrangement to be brought from a closed position on said pourer part to an open and separate position with respect to said pourer part ; - engagement means are provided when said cover part is rotated into said closed position on said pourer part ; wherein - said cover part and said pourer part are produced in a single piece by moulding; - said engagement means are of the breakable type (28,30;228,230) and are arranged partly on said cover part and partly on said pourer part and remain integral with at least one of said parts when they are broken at the first opening, wherein said pourer part comprises an essentially cylindrical section (16,17 and 18) and an actual pouring section , having a reduced diameter with respect to the cylindrical section, connected by a flat annular element or step , extending radially to connect said two portions (16,17 and 18;26), characterized in that on said flat element or step of the pourer part , there is an inverted L-shaped flap element , which extends into a leg facing downwards, wherein said leg in a closed position of said cap is inserted between the cover part and the pourer part so as allow a complete closure between the same, and after a first opening, said leg facing downwards with respect to the axis of the cap is arranged and engages on an external part of a mouth of the container (C) which pushes it towards the outside and opposes their complete closure in contact between the cover part and the pourer part . <EOS>