Liquid Tension Experiment is an instrumental rock project consisting of Dream Theater members John Petrucci (guitar), Jordan Rudess (keyboards), and Mike Portnoy (drums), as well as progressive rock icon Tony Levin (bass, Stick). The combo was formed as a side project to Dream Theater in 1998. The band played fast, fusion-based pieces highly similar to those of Dream Theater (though without lyrics).

Liquid Tension Experiment released two albums, Liquid Tension Experiment (1998) and Liquid Tension Experiment 2 (1999) on Magna Carta records. They also played a few live shows in New York and Los Angeles.