The Lexus RX first premiered in 1997 as a Lexus concept, followed several months later by debut of the production RX 300 models. In 2003, the second generation RX debuted in the U.S., and the redesigned RX 330 went on sale shortly after. In 2004, the RX line added the world's first luxury-type hybrid, the RX 400h, and the RX 330 was upgraded to the RX 350 for model year 2007. Equivalent versions of the first and second generation models were sold in Japan under the Toyota Harrier nameplate until 2008. The redesigned third generation RX 350/RX 450h models premiered in late 2008.
As one of the first luxury SUVs on the market, the Lexus RX has inspired similar competitors from rival marques. Its commercial success as Lexus' best-selling model has been attributed to the strong reliability reputation of Lexus and the RX line. The RX is also the only Lexus vehicle to be produced outside of Japan, with North American market RX 350s being made at the Cambridge plant in Canada. The RX designation, coincidentally similar to the unrelated Mazda RX-7/RX-8 coupes and the Kia Rio RX-V hatchback in Canada, signifies its place in the Lexus lineup next to the larger GX and LX SUVs.
In February 1997, Lexus debuted the "Sport Luxury Vehicle" (SLV) concept, a prototype crossover SUV, at the Chicago Auto Show. This concept, which appeared close to production, combined the characteristics of an SUV, wagon, and sedan. In Japan, the SLV concept appeared in first-generation Harrier form (codename SXU10 and MCU10 for the front wheel drive models, and SXU15 and MCU15 for the four wheel drive models) in December 1997. Two engines were available, the 2.2L 5S-FE I4 which produced 139hp (104kW) JIS (102kW) and 191Nm (140ft·lbf), and the 3.0L 1MZ-FE V6 which produced 219hp (163kW) JIS (161kW) and 304Nm (224ft·lbf). Both engines could be specified with either front or all wheel drive. All models came with an automatic transmission as standard. The vehicle was partly based on the Camry platform.