RER

RER may refer to:

Transport

In France

• , or , the commuter rail service serving Paris and its suburbs
• , now called , commuter rail service serving Geneva (Switzerland), Annemasse (France) and its suburbs

In Belgium

• ('Brussels Regional Express Network'), the commuter rail service serving Brussels and its suburbs and commuters
• ('Ghent Regional Express Network'), the commuter rail service serving Ghent and its suburbs and commuters

In Switzerland

• , the name used for the Bern S-Bahn in French speaking areas.
• , commuter rail service serving Vaud and its suburbs
• , commuter rail service serving Fribourg and its suburbs
• , the name used for the Basel S-Bahn in French speaking areas.
• , now called , commuter rail service serving Geneva, Annemasse and its suburbs

In Argentina

• , a planned commuter rail service in Buenos Aires

In Canada

• GO Regional Express Rail, now known as GO Expansion, a planned commuter rail service in Toronto and its suburbs

Other uses

• Rebuilt Reading electric multiple units
• The Real Estate Roundtable, a non-profit public policy organization that represents the interests of real estate
• Real exchange rate, the purchasing power of a currency relative to another at current exchange rates and prices
• RēR, the standard abbreviation for the label Recommended Records
• Resident Evil: Revelations, a Capcom game
• Respiratory exchange ratio, the ratio between the amount of carbon dioxide produced in metabolism and oxygen used
• Rough endoplasmic reticulum, a type of endoplasmic reticulum protein-manufacturing ribosomes