Lately, the use of wetlands as an alternative way of wastewater treatment has been investigated from several points of view: Biotic (macrophytes and micro-organism) and abiotic (sedimentation). An approach of the current situation of the investigations dealing with this topic is included in this paper. This review also summarizes the role of sedimentation in the improvement of water quality in wetlands. The interest in this subject has increased in the last few years. The investigations are carried out basicaly in constructed and natural wetlands and, to a lesser extent, stu-dies with microcosms in laboratory have also been made. In wetlands, between 23 and 93% of the mineral particles in suspension are retained by sedimentation. Some processes, like N retention, are aparently long-term sustainable while some others, like P retention, could be reversible processes depending on the inputs. In conclusion, a greater effort should be made in order to determinate the water purification capacity of each wetland. Long-term studies should be carried out locally to prevent these ecosystems from collapsing.