Retention of soil in the ground (fabric or foam) or in the pile of polyamide and polypropylene carpets after repeated vacuum cleaning has been measured by a radioactive tracer technique. The soil was a chromic oxide powder containing radioactive ₅₁Cr isotope. The polypropylene carpets could be cleaned just as well as the nylon carpets. Electrostatic behavior of ground and pile was an important factor in soil retention. -- AATA