In this study, the toxicity of colloidal silver nanoparticles produced from three companies (US NANO, Pioneers, Nanonasb Pars) in the larvae of barnacles Amphibalanus amphitrite was evaluated using standard OECD. These crustaceans are important economically and ecologically. In this research, the LC₅₀ within 24 hours for nauplius stages II, III, IV, V and VI examined against toxicity of the three types of silver colloidal nanoparticles. The results suggested that the calculated LC₅₀ of silver nanoparticles from US NANO company for naupli II, III, IV, V and, VI, were 0.077, 0.046, 0.071, 0.006 and,0.009 mg/ml, respectively, and the LC₅₀ of silver nanoparticles from Pioneers company for naupli II, III, IV, V and VI were 0.122,0.5, 0.402, 0.013 and, 0.023 mg/ml, respectively. The evaluated LC₅₀ of silver nanoparticles from Nanonasb Pars for naupli, II, III, IV, V and VI were 0.259, 0.037, 0.018, 0.019 and, 0.017 mg/ml, respectively. This result indicated that silver nanoparticles of US NANO companys have been the most toxic on all larval barnacle stages and should be reviewed in correlation with the environment management products of silver nanoparticles.