Lang Sen Wetland Reserve (Vietnamese language: Khu bảo tồn đất ngập nước Láng Sen) is a wetland area in Dong Thap Muoi, Long An Province, Vietnam.

Lang Sen area is heavily covered with flora varied to the seasonal tides of the Mekong river (Bassac River), especially planted cajuput forest which attracts a diverse fauna to inhabit here.

[3] The diversity of the flora and fauna here has been damaged by the agricultural activities of the local residents, reducing the number of endemic species once lived here.

Since 1998, several researches and surveys have been implemented by local and international organizations in order to collect appropriate proof for the establishment of a natural reserve.

It was also chosen as one of two typical areas of wise biological diversity reserve in Mekong Basin sponsored by IUCN, GEF, UNDP, and MWBP.