Río Pilcomayo National Park, National park and wetland sanctuary in Formosa, Argentina.

Río Pilcomayo National Park is a protected area in Formosa Province that spans grasslands, wetlands, palm forests, and gallery forests. These different habitats support a wide range of plants and animals in this eastern Chaco landscape.

Law 14073, passed on 29 September 1951 and promulgated on 17 October 1951, created the park with 285,000 hectares. On 27 September 1968, law 17915, requested by the Formosa Legislature, cut it to 51,889 hectares and transferred the removed land to the province. Decree 2149/90 of 10 October 1990 made part of the park a strict nature reserve, and decree 453/1994 of 23 March 1994 redrew its limits and created a wild nature reserve.

The park's name comes from the Pilcomayo River, whose floodwaters feed its marshes and lakes. The caranday wax palm, up to 14 m tall with fan-shaped glaucous-green leaves, is treated as an unofficial emblem of the area; parrots and other birds nest in its crowns, and the straw-headed woodpecker and ñenday parrot use holes in its trunks.

Visitors can reach two recreational areas, Estero Poi and Laguna Blanca, with camping facilities, restrooms, and walking trails near Laguna Blanca town. The best time to visit depends on the season, as water levels and wildlife viewing opportunities shift throughout the year.

The park, together with El Impenetrable in Chaco, is one of the last strongholds of the jaguar in the Argentine Chaco. The caranday wax palm, up to 14 m tall, is an unofficial emblem of the area; the straw-headed woodpecker and the ñenday parrot nest in the hollows of its trunks.