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Sweet potato (Ipomoea batatas L. Lam.) presents a great nutritional and economic importance in the tropical regions. It is a source of income for producers and an important food especially in period of welding. In spite of these importances, sweet potato belongs of the underused and neglected species as regards research in Benin. Sampling was carried out at Dangbo, Adjohoun and Bonou in department of Ouémé (south Benin), from August 2016 to May 2017. This study evaluated varietal diversity based on vernacular nominations and production constraints of sweet potato (Ipomoea batatas L. Lam.) in South Benin. Producers are identified using the snowball sampling method. In the first instance, a random draw was carried out among the producers targeted by the head of each of the six villages. Then, each of the selected producers is asked to identify other sweet potato producers. Statistical methods used to measure the varietal diversity include Shannon diversity indice, varietal richness and equitability (abundance). 23 local cultivars were listed including ten (10) regularly cultivated subject to synonymies. Adjohoun has cumulated average richness, index of Shannon and number equivalent most elevated (RC = 38; H = 2.49; Eq.E = 12.10). However, the most elevated equitability and more nearer to 1 (E= 0.71) is obtained at Dangbo. The main constraints enumerated by the producers are absence of flow market, attacks of the devastating and illnesses and the non availability of the quality seeds. For people in the study area, there are several sweet potato cultivars, but are subject to several constraints, in particular those related to pests and diseases, which have a serious impact on the productivity of cultivars, even those be more productive.