Abstract: Suspended ceiling structure for cleanroom comprising a pressurized plenum, the lower face thereof is defined by filter plates supported by a metallic structure having the shape of an horizontal grid, comprising extrusions (P1, P2, P3) crossing at a right angle, said extrusions (P1, P2, P3) having upper channels associated in such a manner that they form a continuous channel around each mesh of the grid and they form a support for a filter plate (13, 13'), said channels (15, 15') being filled with a material in which dips a peripheral support (14, 14') for said filter plate (13, 13') to assure the sealing between the plenum and the volume beneath the ceiling structure, characterized in that each extrusion (P1, P2, P3) comprises at least one horizontal lateral groove (3), upon its full length and having the shape of a slide (2) having at each end housings (4) provided to cooperate with fixation means (5, 6, 7) of a perpendicular extrusion, said fixation means (5, 6, 7,) cooperating also with said slide (2) faci