RER may refer to:
Transport
In France , or , the commuter rail service serving Paris 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. , now called , commuter rail service serving Geneva, Annemasse and its suburbs , commuter rail service serving Fribourg and its suburbs , commuter rail service serving the canton of Jura , the name used for the Basel S-Bahn in French speaking areas. , commuter rail service serving Vaud 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, 2012 video game Resident Evil Requiem, 2026 video 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