| Urdinarrain | |
| Native Name Lang: | es |
| Settlement Type: | City |
| Pushpin Map: | Argentina |
| Pushpin Map Caption: | Location of Urdinarrain in Argentina |
| Coordinates: | -32.6856°N -58.8867°W |
| Subdivision Type: | Country |
| Subdivision Name: |  Argentina |
| Subdivision Type1: | Province |
| Subdivision Type2: | Department |
| Subdivision Name2: | Gualeguaychú |
| Unit Pref: | Metric |
| Population Total: | 8986 |
| Population As Of: | 2010 census |
| Population Density Km2: | auto |
| Timezone1: | ART |
| Utc Offset1: | -3 |
| Postal Code Type: | CPA base |
| Postal Code: | E2826 |
| Area Code Type: | Dialing code |
| Area Code: | +54 3446 |
Urdinarrain is a city in the center-south of the province of Entre Ríos, Argentina, 240 km southeast from the provincial capital Paraná and 40 km west from Gualeguaychú, on Provincial Route 20. It has 8,986 inhabitants as per the .
The original small settlement was populated by many newcomers, mainly European immigrants, after the arrival of the railway line on 23 September 1890. It was declared a first-category municipality on 21 August 1942. The current name of the city is an homage to General Manuel Antonio Urdinarrain (1801–1868), who fought alongside local caudillos Francisco Ramírez and Justo José de Urquiza.