The Patiala and East Punjab States Union (PEPSU) was a State of India, uniting eight princely states between 1948 and 1956. The capital and principal city was Patiala. The state covered an area of 26,208 km². Kasauli, Kandaghat and Chail was also part of PEPSU.

It was created by combining eight princely states (7 Punjab States & 1 Punjab Hill State), which maintained their native rulers :

The state was inaugurated on 15 July 1948 and formally became a state of India in 1950.

On 1 November 1956, PEPSU was merged mostly into Punjab State under the States Reorganisation Act.

A part of the former state of PEPSU, including the present day Jind district (Jind & Narwana), area of Pinjore in north Haryana, as well as the Charkhi Dadri, Bawal and Mahendragarh Narnaul in south-west Haryana, presently lie within the state of Haryana, which was separated from Punjab on 1 November 1966. Some other areas that belonged to PEPSU, notably (Kandaghat etc.) Solan and Nalagarh, now lie in the state of Himachal Pradesh.

When the state was formed, the then-Maharaja of Patiala, Yadavindra Singh, was appointed its Rajpramukh (equivalent to Governor). He remained in office during the entire length of the state's short existence. The then Maharaja of Kapurthala, Jagatjit Singh, served as Uparajpramukh (lieutenant-governor).^{[citation needed]}

Gian Singh Rarewala was sworn in on 13 January 1949 as the first Chief Minister of PEPSU. Col. Raghbir Singh became the next Chief Minister on 23 May 1951, and Brish Bhan the Deputy Chief Minister.

The state elected a 60-member state legislative assembly on 6 January 1952. The Congress Party won 26 seats and the Akali Dal won 19 seats.