Monkey liver ferritin was isolated and purified along with human liver ferritin and their physicochemical and immunological characteristics were compared. The apparent molecular weight of monkey liver ferritin was estimated to be 430 kDa as against 450 kDa of human liver ferritin. Both ferritins appeared to be made up of a 22.5 kDa polypeptide under denaturing conditions and the proteins contained neutral sugar (wt/wt) of 2.0% (monkey) and 2.4% (human). By immunoblots both human and monkey liver ferritins showed appreciable cross-reactivity with the polyclonal antibodies raised against either proteins. Monkey liver ferritin, however, was not recognised by the human monoclonal antibody. The amino acid composition of both ferritins was more or less similar. Isoelectric focusing indicated that monkey liver ferritin showed microheterogeneity with three bands at pI 5.4, 5.5 and 5.6, whereas human liver ferritin showed a single band at pI 5.6 confirming the relative acidic nature of monkey liver ferritin.