AMSTeX is a TeX macro package, originally written by Michael Spivak for the American Mathematical Society (AMS) during 1983–1985 and is described in the book ‘The Joy of TeX’. It is based on Plain TeX, and provides many features for producing more professional-looking maths formulas with less burden on authors.

More recently, the focus of attention has switched to amslatex, but AMSTeX remains as a working system.

The author is The American Mathematical Society. The package is Copyright © 1985,1990,1991,2001 American Mathematical Society.