Rb or RB may stand for:

In science and computing:

  • Rebar (short for reinforcing bar), also known as reinforcing steel, reinforcement steel, a common steel bar, and is used in reinforced concrete structures
  • Retinoblastoma, a childhood cancer of the eyes caused by a mutation in the retinoblastoma protein
  • Retinoblastoma protein, a tumor suppressor protein
  • Rubidium, a chemical element
  • .rb, the file extension for documents created in Ruby

In transport and vehicles:

  • RB, the IATA airline code for Syrian Arab Airlines
  • Hyundai RB (buses), a series of Korean buses
  • Nissan RB engine, a gasoline engine made by Nissan
  • Réseau Breton, a French railway network in Brittany
  • SJ Rb, a Swedish locomotive
  • Regionalbahn, a type of train in Germany

In other uses:

  • Parti de la Renaissance du Bénin or Benin Rebirth Party, a political party in Benin
  • Rancho Bernardo, a community in San Diego, California, United States
  • Running back, a position in American football
  • Right back, a defensive position in association football
  • Ray-Ban, a sunglasses company
  • Rock Band, a music video game series or Rock Band (video game), the game of the same name
  • Rowboat
  • Rebecca Freed, a RA from Wiley Residence Hall at Purdue University
  • Rebecca Black, an American pop star
  • Rupiah Banda, current President of Zambia
  • Reckitt Benckiser, a company in United Kingdom
  • República Bolivariana, Spanish-language phrase for the type of government in Venezuela.