Abstract: Apparatus for disinfecting medical apparatus, and especially artificial respirators, by the action of formaldehyde fumes subsequently neutralized by ammonia fumes, the apparatus being adapted to avoid the deposition of crystalline hexamethylene tetramine inside the respirator and comprising an enclosure for receiving the medical apparatus, a source of formaldehyde fumes likely to spread within the enclosure, and an auxiliary neutralization chamber communicating with the enclosure and provided with a source of ammonia; the volume of the neutralization chamber being such as to allow ammonia fumes to spread and to come into contact with formaldehyde fumes for a sufficient time to ensure neutralization.