Bag-in/Bag-out system is a specific safe containment procedure to maintain confinement while removing contaminated filters from a cytotoxic safety cabinet or a glovebox cabinet. The bags are used to seal the stainless steel canister located below working surface, avoiding the operators to come into direct contact with any toxic materials. The bag is sealed to a flange at the door opening of the containment section with a shock cord. Contaminated filter is removed from their mount in the canister housing and slid into the bag. The bag is then sealed and removed and a new bag is mounted to the flange. The door is then closed and sealed and the unit placed back into service. Bag-in/Bag-out system is the safest and most practical way for replacing hazardous contaminated filters.