Consecutive layers of cationic polyallylamine and anionic polyacrylic acid have been deposited on both unbeaten and beaten fully bleached cellulosic fibres. By preparing sheets of these fibres and by forming 5-10 layers of these polyelectrolytes on the unbeaten fibres, it was possible to develop the same strength as can be achieved by conventional beating. Experiments show that considerable strength improvement can be achieved with this type of treatment also on beaten fibres. Atomic force microscopy investigations of multilayers of the polylectrolytes formed on silicon oxide surfaces showed that the thickness of 10 layers of polyelectrolytes was 52 nm. Since the strength improvement was significant with 5 layers, it is suggested that a 26 nm thick multilayer of polyelectrolytes is sufficient to create a strong joint between fibres. The structure of the polyelectrolyte multilayers formed on the fibres was not determined.