Lennard-Jones fluid adsorption in bounded slits has been calculated by the Monte Carlo method. Isotherms of methane adsorption in circular finite carbon slits with different widths have been calculated in a wide pressure range. For finite slits, the contribution of edge effects to the adsorption behavior of methane has been estimated as compared with infinite slits. Qualitative agreement with the conclusions of the asymptotic theory has been reached for the behavior of local density in finite slits.