Sperm cell and embryo toxicity tests using the sea urchin Strongylocentrotus intermedius (S. intermedius) were performed to assess the toxicity of indoxacarb, a new widely used insecticide. New toxicity data for indoxacarb expressed as median effective concentration (EC(50)) were reported for the sea urchin species. When sperms and cells were exposed to the pesticide before fertilization, no significant inhibition in the fertilization success of S. intermedius (up to 40 mg/L) was observed. Developmental toxicity of the pesticide displayed a significant dose-related increase of larval malformations and differentiation arrest at concentrations of 0.1 mg/L to 40.0 mg/L at each cleavage, including the 2-cell stage, 4-cell, blastula, gastrula, prism and 4-arm pluteus stages. It seems that 4-arm pluteus is the most sensitive to indoxacarb with the EC(50) of 3.73 mg/L, two times less than that of the first cleavage stage. All these results indicate that more attentions should be paid to the potential marine pollutions caused by this pesticide indoxacarb.