The invention concerns a protective headgear comprising a respirator (2) capable of being connected to a breathing mixture source, an eye protecting shield (5) and first (32) and second (56) lock elements, respectively located on the respirator (2) and on the shield (6) and adapted to co-operate with each other to secure the shield (6) to the respirator (2), when the respirator is in its use position on the user's face, the first (32) and second (56) lock elements being adapted to be mutually engaged and interlocked by a movement bringing the shield (6) closer to the respirator (2), from above.