This paper examines the effects of treatments inducing the reduction of salts and the organic content on the Atterberg limits of marine dredged sediments. To define the liquid limits of the sediments, the results of the percussion-cup test and the fall cone test are compared for raw sediments and treated sediments. For the determination of the plastic limit, the results of the rolling test method are compared to the prediction of the fall cone test. Finally, the relationship between the water contents and the penetration depths between the liquid limit and the plastic limit is explored.