We report a morphometric study on the effect of 3-palmitoyl-(+)-catechin on phagocytic activity of latex particles by Kupffer cells in guinea pig liver. We found an increase in the density of latex particles in Kupffer cells of animals treated with 3-palmitoyl-(+)-catechin. The volume and density of Kupffer cells of treated animals increased (p < 0.01); there was no significant difference in surface density of the plasma membrane. None of the parameters measured was altered in endo-thelial cells. These results show that 3-palmitoyl-(+)-catechin produces morphological and functional changes in Kupffer cells.