Muang Sam Sip (Thai: ม่วงสามสิบ, pronounced [mûaŋ sǎːm sìp]; Northeastern Thai: ม่วงสามสิบ, pronounced [mūaŋ sǎːm si᷇p]) is a district (amphoe) in the northwestern part of Ubon Ratchathani province, northeastern Thailand.

Four years later, the district name was changed back to Kasem Sima.

Neighboring districts are (from the east clockwise) Lao Suea Kok, Mueang Ubon Ratchathani, Khueang Nai of Ubon Ratchathani Province and Hua Taphan, Lue Amnat and Phana of Amnat Charoen province.

The district is divided into 14 sub-districts (tambons), which are further subdivided into 158 villages (mubans).

This Ubon Ratchathani Province location article is a stub.