Langmuit-Blodgett (LB) films of various amphiphiles were prepared on molecularly smooth mica sheets, and interactions between these films were measured directly using surface forces apparatus. Very long range attraction extending close to 300 nm was found between two hydrophobic monolayers of a polamerized ammonium amphiphile in pure water. Surface structure and adhesive properties of hydrophilic bilayers of the identical amphiphile were also studied. This polymerized layer displayed weak adhesion of 1-5 mN/m. Using monolayers of a poly(methacrylic acid) amphiphile, it was possible to measure pH-induced changes in effective forces, reflecting different ionization states of the polyelectrolyte. The direct force measurement is a powerful means to study structures and interactions of LB film surfaces at the nanometer scale, and LB modification has high potential to prepare novel surfaces for measurement of forces.