ABSTRACT This study investigates the liquid limit (Casagrande's method) and plastic limit (rolling and thread method) of six inorganic soils and their respective mixtures with fine silica sand. It was observed that the liquid limit and plastic limit values of the mixtures tested, except those with a low clay percentage, are linked to the respective clay size contents by a linear relationship. The Atterberg limits were subsequently recalculated using the equations of the regression lines of the mixtures governed by linear law with the clay percentages. The plotting of the plastic limit as a function of the liquid limit of these data made it possible to determine the relationship among the liquid limit, the plastic limit and clay fraction valid for inorganic soils that contain platey clay minerals and for clay size contents that are not too low. Hence, on the basis of the interdependence among the parameters considered (WL, Wp, Ip, CF, A), for a given inorganic soil, knowing only two of three parameters (WL, Wp, CF) that are measurable using standard tests, the values of other three parameters can be obtained.