• PRB (car), the Australian Automotive Manufacturer
• PRB (vessel)
• The unofficial ISO 4217 code for the Transnistrian ruble

PRB is short for:

• Powder River Basin, a major coal producing geologic basin in the USA
• Brazilian Republican Party, (Partido Republicano Brasileiro, in Portuguese)
• Pre-Raphaelite Brotherhood, a group of English painters, poets and critics, founded in 1848 by John Everett Millais, Dante Gabriel Rossetti and William Holman Hunt
• Population Reference Bureau
• Parti Rakyat Brunei, a now extinct political party in Brunei
• Physical Review B
• Retinoblastoma protein pRb or Rb, is a tumor suppressor protein found to be dysfunctional in a number of types of cancer
• The People's Republic of Boulder, a common nickname for Boulder, Colorado