In this article, We prove the reliability of hybrid models in loss
reserving, especially when the data contain fuzziness for example when the claims are related to body injures . We estimate a hybrid log-linear model (log-Poisson) using the fuzzy least-squares (FLS) procedures [10,11, 22,23]. We develop a new goodness of fit index to compare this new model and the classical log-Poisson regression in loss reserving framework . Both the classical log-Poisson model and the hybrid one are performed on a loss reserving data. According to the goodness of fit index and the Mean Square Error, we prove that the new model provide better results than the log-Poisson model.