Due to their intentional or accidental release to aquatic environments, exposure of aquatic organisms to releasednanomaterials (NMs) is increasing day by day. Both silver nanoparticles (Ag NPs) and titanium dioxide nanoparticles(TiO2 NPs) are commonly used in consumer nanoproducts and although there are reports about their possible toxicityon aquatic organisms, but their co-exposure effects not yet well understood. In this work we exposed juvenile Commoncarp (Cyprinuscarpio) according to the general rules mentioned in OECD 203, to 0 (control), 0.05, 0.1, 0.15, 0.20, 0.25,0.30, and 0.35 mg/L Ag NPs solely or in binary mixture with 1 mg/L TiO2 NPs. The mortality rates of the fish weremonitored for 96 hours and the data were analyzed to calculate median lethal concentrations (LC50s) using EPA ProbitAnalysis software. The 96 hr LC50s of Ag NPs alone and in combination with TiO2 NPs were estimated at 0.388±0.107and 0.187±0.006 mg/L, respectively, which shows significant increase of joint toxicity of these two NMs. In the otherwords, titanium dioxide nanoparticles have increased acute toxicity of silver nanoparticles in juvenile common carp. Ourresults revealed that although TiO2 NPs are known as none or low toxicity NM for most studied aquatic organisms, theymay pose potential environmental impact throw increasing toxicities of other pollutants including other NMs.