A new rapid method is described for the isolation and purification of rat and human Kupffer cells without the need of liver perfusion techniques. Rat livers or small human liver wedge biopsies obtained peroperatively were incubated with pronase under continuous pH registration. Kupffer cells were subsequently separated from other nonparenchymal cells by Nycodenz gradient centrifugation and purified by counterflow centrifugal elutriation. Identification of Kupffer cells was achieved on the basis of ultrastructural analyses and immunophenotyping.