The Nissan 240SX is a sports compact car that was introduced to the North American market by Nissan in 1989 for the 1990 model year. It replaced the outgoing 200SX (S12) model. Most of the 240SXs were equipped with the 2.4-liter inline 4 engine (KA24E from 1989 to 1990 and KA24DE from 1990 to 1998). The KA24E had single overhead cams and the KA24DE had dual overhead cams. Two distinct generations of the 240SX, the S13 (1989–1994) the S14 (1994-1998) were produced, based on the Nissan S platform.

The 240SX is closely related to other S platform based vehicles, such as the Japanese-market Silvia and 180SX, and the European-market 200SX. Although their names are similar, the 240SX is unrelated to the 240Z or the 280ZX.

While the car is no longer being produced since 1998, it remains popular in drifting and tuner culture. However, due to the popularity of the S-chassis in drifting or other related competitions, prices for vehicles and parts have greatly increased because of higher demand of the vehicles or parts. This problem is sometimes known as drift tax.[citation needed]

Because of its extreme popularity in drifting or similar competitions, the 240SX is featured in numerous racing video games such as Midnight Club and Forza Motorsport, among others.