UDP may refer to:
in political parties:
- United Democratic Party, one of multiple organizations
- Ulster Democratic Party, in Northern Ireland
- Democratic and Popular Union (Spanish: Unidad Democrática y Popular) a former Bolivian umbrella party
- People's Democratic Union (Portugal)
on the Internet:
- User Datagram Protocol, a network communications method
- Usenet Death Penalty, a discussion group disciplinary response
in other uses:
- Unit Deployment Program, a military assignment system
- Unitary development plan, a land use planning system
- Uridine diphosphate, an organic chemical
- Diego Portales University, a school