The measurement of the total cross section and of the machine luminosity is the first objective of the experiment TOTEM [1] [2]. The total cross section will be measured with the luminosity independent method based on the simultaneous measurement of low momentum transfer elastic scattering and of the rate of inelastic interactions with fully inclusive trigger. Elastic scattering events will be detected with the Roman pot technique using a suitable machine optics obtained by properly tuning the quadrupoles in the intersection region. The measurement of the total cross section will be followed in due course by the study of elastic scattering at large momentum transfer and of diffractive processes.