Superfluorescent decay in a weakly disordered slab is considered. By solving the Maxwell-Bloch equations we show, that the cooperation number increases with increasing of the mean free path. Superfluorescent impulse is emitted at a small angle to the slab, isotropically in a plane direction. PACS.42.20-Propagation and transmission in inhomogeneous media. PACS.42.20G-Scattering, diffraction and polarization. Introduction. During the spontaneous emission of uncorrelated exited atoms, their dipole moments interact each other via the emitted electromagnetic field. If the lifetime of exited state is long enough, the radiation can induce the correlation between the group of large number Nc (so called cooperation