The authors demonstrate that parity-time (PT) symmetric Bragg periodic structures near the spontaneous PT-symmetry breaking point can act as unidirectional invisible media. In this regime, reflection from one end is diminished while it is enhanced from the other. The transmission coefficient and phase remain unchanged, similar to the absence of a grating. This phenomenon is robust even in the presence of Kerr non-linearities and can effectively suppress optical bistabilities. The study explores the scattering from PT-symmetric Bragg structures, showing that at the PT-symmetry breaking point, the system is reflectionless for left incidence and has enhanced reflection for right incidence. The transmission phase vanishes, making the structure invisible. Numerical simulations confirm these findings, and the robustness of the unidirectional invisibility is demonstrated in the nonlinear regime.The authors demonstrate that parity-time (PT) symmetric Bragg periodic structures near the spontaneous PT-symmetry breaking point can act as unidirectional invisible media. In this regime, reflection from one end is diminished while it is enhanced from the other. The transmission coefficient and phase remain unchanged, similar to the absence of a grating. This phenomenon is robust even in the presence of Kerr non-linearities and can effectively suppress optical bistabilities. The study explores the scattering from PT-symmetric Bragg structures, showing that at the PT-symmetry breaking point, the system is reflectionless for left incidence and has enhanced reflection for right incidence. The transmission phase vanishes, making the structure invisible. Numerical simulations confirm these findings, and the robustness of the unidirectional invisibility is demonstrated in the nonlinear regime.