Butyl benzyl phthalate (BBP) is a diester of phthalic acid commonly used to increase the flexibility and elasticity of plastics. BBP is found in a variety of everyday items like food packaging, perfumes, toys, cosmetics, medical devices, electronics, flooring and carpeting. Environmental presence of BBP has also been noted as it can seep into the soil and contaminate groundwater. Sediment and water analysis has noted high levels of BBP and BBP has been detected in human blood and breast milk. Given the widespread uses of and exposure to BBP, studies on developmental toxicity are needed. To that end, we sought to investigate the developmental effects of BBP exposure during early development utilizing the zebrafish vertebrate model system. We treated gastrula staged embryos with increasing concentrations of BBP and noted concentration dependent defects in caudal tail development, but the effect was caudal specific with no other developmental defects noted. In situ hybridization studies using muscle and notochord markers show alterations in muscle fibers and non-linear, kinked tail staining. A more detailed antibody staining using a myosin specific marker shows alterations in myofibril arrangement with either disorganized and/or loss of myofibril segments. Apoptotic staining demonstrated a concentration dependent increase in apoptotic spots in the developing tail. Furthermore, vascular development in the tail was also disrupted in a concentration dependent manner. We conclude that BBP, at environmentally relevant doses, is toxic to caudal development in zebrafish.