The invention relates to a pressure-relief valve of a housing for an electrical/electronic unit, particularly for a housing of a control unit of a motor vehicle, comprising a pressure equalization element, which comprises a membrane. It is provided that at least one hydrophobic layer (22) is located on the membrane (21). The invention further relates to a housing (1) for an electrical/electronic unit (2), particularly of a control unit (4) of a motor vehicle, comprising such a pressure-relief valve (11).