Riserva naturale Valle del Fiume Argentino, State nature reserve in Province of Cosenza, Italy.

The Riserva naturale Valle del Fiume Argentino is a protected area in the mountains of Cosenza province featuring dense forests, river valleys, and limestone caves. The landscape mixes steep terrain with thick woodlands and rocky outcrops, cut through by flowing water systems.

The reserve was established by ministerial decree on 21 July 1987 (D.M. 21.07.87) and covers 3,980 hectares in the municipality of Orsomarso, province of Cosenza. It lies within the Parco nazionale del Pollino, near the mountains of Lungro, and protects the valley of the Argentino river and its native roe deer population.

The reserve's name comes from the Argentino river that runs through its valley. The Grotta Madonna di Lourdes holds a statue of the Madonna set among stalactites, and visitors also come for the panoramic view from the cave. The valley is the heart of the small area where the last native Apennine roe deer survive, estimated at a few dozen animals.

The reserve covers 3,980 hectares in the municipality of Orsomarso and serves as a starting point for hiking routes in this part of the Pollino National Park. Trekking follows the gorges of the Argentino river, while canoeing and rafting take place on the rapids of the nearby Lao river. Paths are on foot only, so wear sturdy boots for rocky ground.

Pietra Campanara is a rock parallelepiped on the slopes of Palanud, and the Grotta Madonna di Lourdes holds a statue among stalactites with a wide panoramic view. The Laghetto di Tavolara and the Cascata Ficara are the other named stops in the valley.