Vitellogenin induction in aquatic male vertebrates has been used extensively as biomarker of exposure to endocrine disruptors exposure. Kidd and collaborator's works (2007) have recently shown that induction of this marker may caused long term population impact. Whereas this approach is well developed in vertebrates, few investigations were lead on aquatic invertebrates species although they represent about 95% of living species and play important roles in ecosystems. Moreover, because of evolutive distances in terms of molecular sequences and functional divergence between endocrine systems, invertebrates cannot be regarded as simple surrogates for vertebrates when considering biomarker responses related to toxic effect, and biomarkers or biomarkers-like should be re-confirmed and re-validated both for their molecular identification and for the interpretation in terms of biological function they could track. This study was the first step for the development of endocrine disruptor biomarker in order to propose a tool for reproductive impact assessment in crustacean. For this, a analytical methodology using mass spectrometry has been proposed to detect and quantify vtg protein in this species. In female, the functionality of this protein has been checked by assessing the level of this protein during the vitellogenesis processes and after an exposure to methyl farnesoate. In the second step and to propose a methodology in males for biomonitoring studies, we investigated the impact of biotic (size, gametogenesis status) and abiotic (physico-chemical characteristics of water) factors to understand the natural variability of this marker. Effects of a suspected endocrine disruptor on the Vtg level in gammarid male and its impact on the spermatogenesis will be presented.