The aim of this study was to assess the impact of adoption of new high-yielding varieties (NERICA) of rice on its varietal diversity in Benin. The database was from Impact Assessment unit of AfricaRice and concerns 304 producers of rice. Overall the study covered twenty-four villages over three districts: Dassa-Zounmè, Glazoué and Savalou. Data analysis was carried out using the econometric approach based on the Local Average Effect of Treatment (LATE) framework. Overall, estimation of impact showed that at village level the indexes of in-situ (on farm) conservation of varietal diversity of rice are the same in NERICA and Non-NERICA villages. Moreover, at farmer level, the average impact of NERICA adoption on number of modern rice varieties of the sub-population of NERICA potential adopters is 0.8. NERICA’s rice varieties had positively impacted the in situ conservation of varietal diversity. Our findings indicated that it is worth extending diffusion of NERICA varieties in Benin.