| Conventional Long Name: | United State of Matsya |
| Common Name: | Matsya Union |
| Nation: | India |
| Status Text: | State of India |
| Year Start: | 1948 |
| Date Start: | 18 March |
| Event Start: | Merger of former princely states, Alwar, Bharatpur, Dholpur, and Karauli after accession |
| Year End: | 1949 |
| Date End: | 15 May |
| Event End: | Merger into Greater Rajasthan |
| P1: | Alwar State |
| P2: | Bharatpur State |
| P3: | Dholpur State |
| P4: | Karauli State |
| S1: | United State of Rajasthan |
| Flag P1: | Alwar flag.svg |
| Flag P2: | Flag of Bharatpur1.png |
| Flag P3: | Dholpur flag.svg |
| Flag P4: | Flag of Karauli.svg |
| Flag S1: | Flag of India.svg |
| Capital: | Alwar |
| Today: | India Rajasthan |
The United States of Matsya, also called Matsya Union or Matsya Sangh, was a State of India which was formed on 18 March 1948 by the merger of four erstwhile princely states, Alwar, Bharatpur, Dholpur, and Karauli after accession.[1] [2] Shobha Ram Kumawat of Indian National Congress was the first and last chief minister of the State from 18 March 1948 till 15 May 1949.[1] Maharaja of Dholpur became its Rajpramukh.
On 15 May 1949, the Matsya Union was merged with Greater Rajasthan,[3] to form the United State of Rajasthan, which later became the state of Rajasthan on 26 January 1950.[4]