Further investigation of the pellicle formed in 2 h on cleaned human teeth in vivo is reported. Electron micrographs demonstrating the presence of a thin organic layer 2 h after the teeth were brushed with pumice are shown. The pellicle material contained several sugars, with glucose as the most abundant. Material from secretors and non-secretors of blood group substances was analysed, but no difference in carbohydrate composition was found. Tests for biological activities indicated the presence of blood group substance and virus haemagglutination inhibition activities in the 2-hour pellicle.