A hypo-allergenic vacuum cleaner is one which removes dust & allergen particles from your floors, while keeping the suctioned particles from escaping the vacuum.  Bagged hypo-allergenic vacuum cleaners do especially well at keeping those particles inside, although there are a few bagless models available. Most newer units will come with a HEPA filter. This filter helps keep any particles from escaping when the air is exiting the machine.

Oreck is the main company making hypo-allergenic vacuums - and probably the best at it. However, there are other manufacturers out there as well. Miele, Dyson, Hoover and Garry are a few other companies with models on the market.

If I were to recommend a unit, it would be the Oreck XL Silver Power Team. It’s on the higher-end of the price spectrum, but does a good job and looks great. Besides having a hypo-allergenic filtration system, it also has antimicrobial protection and is pretty light-weight.