Abstract: A device for breathing and possibly providing NBC protection, the device comprising a mouth-and-nose mask with a breathing gas admission and a breathe-out outlet provided with a breathe-out check valve and with a breathing gas coupling piece carried by an element which is distinct from the mask and worn directly on the head. The coupling piece includes a passage that is connectable in airtight manner to the mouth-and-nose mask feed and a lateral pipe (34) taking the connection with the breathing gas feed (32) rearwards.