Palaemon macrodactylus (Oriental Shrimp), native to estuarine waters of Southeast Asia, has been reported outside of its native range. The spreading of this species to new regions has been well documented, and its disjunct distribution strongly speaks for its transport being attributed to ballast water. In this paper, we report the first record of P. macrodactylus from the eastern coast of the United States and in the estuarine system of New York City (NYC). While this animal has been reported to have crossed the Pacific, and has been found in the eastern Atlantic along the coasts of Spain, France, Germany, and the British Isles, and in the southwestern Atlantic off the coast of Argentina, it has not been previously sighted in the northwest Atlantic. Our preliminary life-history data indicate that the size range for the 98 adult individuals in the 2001 collection was from 2.05 to 5.05 cm, and exhibited a one-to-one sex ratio. The finding of gravid females among these shrimp collected from 2001–2002 and again in 2008 indicates that the oriental shrimp populations in the coastal waters of NYC have become established, and show reproductive activity from May through October. Further studies are required to evaluate whether P. macrodactylus poses a threat to native aquatic organisms in this region.