The interaction between cellulose surfaces is of fundamental interest in various natural and industrial systems. In this study, we describe the first direct measurements of an attractive van der Waals-type interaction between cellulose surfaces under aqueous conditions. An atomic force microscope, operating in colloidal probe mode, has been used to measure these interactions. The interaction between the cellulose surfaces is monotonically attractive at all surface separations. This long-range attractive interaction can be satisfactorily fitted with a Hamaker constant of 3.5 x 10-21 J.