A fire door to be installed in a building, and comprising: at least one panel (2, 202, 302, 402, 502, 602) equipped with a slide part (3, 203, 303, 403, 503, 603) above, comprising slide means (30, 230, 330, 430, 530, 630) and at least one connection member (31, 231, 331, 431, 531, 631) to connect said slide means (30, 230, 330, 430, 530, 630) to said panel (2, 202, 302, 402, 502, 602); a slide guide (4, 204, 304, 404, 504, 604) on which said slide means (30, 230, 330, 430, 530, 630) can slide; and a smoke seal device (5, 205, 305, 405, 505, 605) fixed to said slide part (3, 203, 303, 403, 503, 603) of said panel (2, 202, 302, 402, 502, 602) and comprising: at least one metal profile bar (50, 250, 350, 450, 550, 650) fixed to said slide part (3, 203, 303, 403, 503, 603) and having such length as to cover said slide part (3, 203, 303, 403, 503, 603) all along the length of said door (1, 201, 301, 401, 501, 601), and such height as to cover at least the area between the upper edge of said panel (2, 202, 302, 402, 502, 602) and said slide means (30, 230, 330, 430, 530, 630); and at least one smoke block element (51, 251, 351, 451, 551, 651) having a length greater than or equal to the length of said door (1, 201, 301, 401, 501, 601) and extending transversally from said door (1, 201, 301, 401, 501, 601), said door (1,201,301,401,501,601) being characterized in that said smoke block element (51,251,351,451,551,651) comprises at least one portion (51A, 251A, 351A, 451A, 551A, 651A) flush with at least a portion (42, 242, 342, 442, 542, 642) of said slide guide (4, 204, 304, 404, 504, 604), and in that said smoke block element (5, 251, 351, 451, 551, 651) is suitable for co-operating with said slide guide (4, 204, 304, 404,504, 604) to block cold smokes. at least one panel (2, 202, 302, 402, 502, 602) equipped with a slide part (3, 203, 303, 403, 503, 603) above, comprising slide means (30, 230, 330, 430, 530, 630) and at least one connection member (31, 231, 331, 431, 531, 631) to connect said slide means (30, 230, 330, 430, 530, 630) to said panel (2, 202, 302, 402, 502, 602); a slide guide (4, 204, 304, 404, 504, 604) on which said slide means (30, 230, 330, 430, 530, 630) can slide; and a smoke seal device (5, 205, 305, 405, 505, 605) fixed to said slide part (3, 203, 303, 403, 503, 603) of said panel (2, 202, 302, 402, 502, 602) and comprising: at least one metal profile bar (50, 250, 350, 450, 550, 650) fixed to said slide part (3, 203, 303, 403, 503, 603) and having such length as to cover said slide part (3, 203, 303, 403, 503, 603) all along the length of said door (1, 201, 301, 401, 501, 601), and such height as to cover at least the area between the upper edge of said panel (2, 202, 302, 402, 502, 602) and said slide means (30, 230, 330, 430, 530, 630); and at least one smoke block element (51, 251, 351, 451, 551, 651) having a length greater than or equal to the length of said door (1, 201, 301, 401, 501, 601) and extending transversally from said door (1, 201, 301, 401, 501, 601), at least one metal profile bar (50, 250, 350, 450, 550, 650) fixed to said slide part (3, 203, 303, 403, 503, 603) and having such length as to cover said slide part (3, 203, 303, 403, 503, 603) all along the length of said door (1, 201, 301, 401, 501, 601), and such height as to cover at least the area between the upper edge of said panel (2, 202, 302, 402, 502, 602) and said slide means (30, 230, 330, 430, 530, 630); and at least one smoke block element (51, 251, 351, 451, 551, 651) having a length greater than or equal to the length of said door (1, 201, 301, 401, 501, 601) and extending transversally from said door (1, 201, 301, 401, 501, 601), said door (1,201,301,401,501,601) being characterized in that said smoke block element (51,251,351,451,551,651) comprises at least one portion (51A, 251A, 351A, 451A, 551A, 651A) flush with at least a portion (42, 242, 342, 442, 542, 642) of said slide guide (4, 204, 304, 404, 504, 604), and in that said smoke block element (5, 251, 351, 451, 551, 651) is suitable for co-operating with said slide guide (4, 204, 304, 404,504, 604) to block cold smokes.