Aims: To appreciate the evolution of weight gain by malnourished children and factors associated to children underweight after the Positive Deviance/Hearth sessions. Study Design: Longitudinal study. Place and Duration of Study: Districts Ze and Lalo (Southern Benin), from May to August 2014 Methodology: This study was conducted on 98 children aged of 6-59 months who fully participated in Positive Deviance/Hearth (PD/H). During one month, four measurements of weight have been taken on the 77th, 84th, 91th, and 98th day after the beginning of PD/H. Questionnaire was administered to mother on environmental, hygiene practices, and food accessibility of household. Relation among factors of food accessibility, household hygiene, and child nutritional status was sought by an Analysis of Factorial Components. Results: The children who participated in 12 days of PD/H gained significantly 0.63 kg and 1.13 kg of weight in Lalo and Ze respectively (P<.001). From the 12th to 77th day after the end of PD/H, we noticed a significant weight loss from 10.54 to 10.09 kg in Ze and from 9.75 to 9.19 Kg in Lalo (P=.003). Prevalence of underweight children on the 77th day was 45.8% with 12.5% of severe case and 63.5% with 18.9% of severe case in Lalo and Ze, respectively. The severe underweight children were characterized by households where i) it rarely arrived to be without food ii) one member rarely have a day without eaten but iii) the drinking water is from well. Conclusion: On the 77th day after the PD/H, the children of our study had weight loss. Food accessibility and household hygiene are mainly the limited factors that could explain the degradation of the nutritional status of children and high prevalence of underweight. This first study conducted in Benin on PD/H approach is more exploratory and helps to appreciate this approach efficacy and sustainability.