The pore fluid salinity level of undisturbed Champlain Sea clay samples were reduced from 19.81 to 0.79 g/L using a leaching apparatus designed for this experimental study. Then the impact of leaching on the compressibility characteristics of the undisturbed, remoulded, and cement-treated clay samples were investigated through constant rate of strain tests. It was found that the compressibility of Champlain Sea clay was affected by the level of salinity in its pore fluid. The reduction of salinity to 0.79 g/L in this study impacted the compressibility of both remoulded and cement-treated clay but did not affect on the compressibility of undisturbed clay. A higher compressibility was recorded from remoulded leached sample compared to the remoulded unleached sample. In cement-treated samples, an improvement in the compressibility characteristics was observed from the leached samples treated with 50 kg/m3 GU cement compared to that of their corresponding treated unleached samples.