Biomarkers are useful tools for understanding complex interactions that elicit organisms response to environmental pollutants and their sublethal effects on organisms health. Effect of naphthalene on vitellogenin (VTG) and vitellin (VTN) were assessed in hepatopancreas, haemolymph and ovary of an estuarine crab Scylla serrata with reference to vitellogenic phases. In addition, the gonadosomatic index (GSI) was also assessed. Significant reductions in VTG and VTN contents were observed in hepatopancreas, haemolymph (VTG) and ovary (VTN). The GSI exhibited a decreasing trend in crabs exposed to naphthalene irrespective of the vitellogenic phases. We attempted to use the alterations in vitellogenic proteins and GSI as biomarkers of reproductive disturbances occurred in the crab due to naphthalene stress.