Arroyo del Medio is a stream located in the province of Misiones, Argentina, flowing through the departments of Cainguás and Oberá. Its course extends approximately 62 kilometers from source to mouth.

The stream originates along the watershed of the sierra de Misiones in the municipality of Campo Grande, at an elevation of roughly 450 meters above sea level (coordinates 27°11′28″S 58°05′22″W). From its headwaters, it descends gradually across the central plateau, crossing Ruta Nacional 14 near kilometer marker 909.5. After passing beneath that highway, it receives the waters of Arroyo Aguas Dulces on its left bank.

The stream's character changes notably along its course. In its upper reaches it follows a northwest-to-southeast orientation before shifting to a southward direction. As it progresses, the valley becomes increasingly sinuous and the channel progressively more incised, eventually forming a confined, canyon-like section. Right-bank tributaries along this stretch include Arroyo De la Cruz and Arroyo Yazá, while left-bank tributaries include Arroyo Padilla, Arroyo Grapia, Arroyo Aguas Dulce (Chiquero), Arroyo Rosa, Arroyo Tarumita, and Arroyo Tres Pasos. Additional right-bank tributaries include Arroyo Persiguero.

The stream terminates at its confluence with Arroyo Acaraguá near the municipal balneario (public bathing area) of Campo Ramón, at an elevation of approximately 140 meters above sea level (coordinates 27°26′37″S 54°55′31″W). The presence of a municipal balneario near the mouth suggests some level of public access and basic facilities in that area.

The drop from source to mouth — roughly 310 meters over 62 kilometers — indicates a moderate average gradient, though the increasingly incised lower valley suggests steeper and more technical sections downstream. Paddlers considering this stream should be aware that the confined canyon character of the lower reaches could present significant hydraulic challenges, particularly during periods of elevated flow.