Quadruplex may refer to:
- Quadruplex telegraph, an improvement on the electrical telegraph patented in 1874 by Thomas Edison
- Two-inch quadruplex videotape, the first practical and commercially successful videotape format
- G-quadruplex, the four-stranded nucleic acid structure that is, among scientists, sometimes referred to as a quadruplex.
"Quadruplex" can also refer to a building split into four apartments, similar to a duplex