Arroyo Ramallo is a stream located in the Buenos Aires province of Argentina, flowing through the Pampas region and ultimately connecting with the broader river system of the Río Paraná drainage. This waterway is part of a network of productive lowland streams that characterize the northeastern Buenos Aires province, offering anglers access to some of the most sought-after sportfish in South America. The stream shares its name with the nearby Zanjón Ramallo, and both waters are recognized among local anglers as productive destinations within the same general area.