Bisphenol-A (BPA) is one of the important industrial chemicals used in manufacture of polycarbonate, epoxy resins, and in the packing industry. It is released into the environment from the industries producing or incorporating BPA, and reaches detectable levels in aquatic environments. In this investigation, the embryo-toxic effects of BPA were analyzed during the development of the sea urchin Arbacia lixula from the post-fertilization to pluteus stage (72 h). Sea urchin embryos were exposed to BPA concentrations ranging from 5 to 3500 mu g/L. The effects on developing embryos were evaluated by scoring normal plutei and developmental defects, such as retarded plutei, skeletal malformations, blocked gastrula/blastula and dead embryos/larvae. Following exposure to BPA, a concentration-related increase in the number of larvae with skeletal malformations at pluteus stage was observed. The EC50 for 72 h was determined to be 1396 mu g/L, and the NOEL (no observable effect level) 70 mu g/L.