UK TeX FAQ -- question 165

### Roman theorems

If you want to take advantage of the powerful `\newtheorem` command without the constraint that the contents of the theorem is in a sloped font (for example, to use it to create remarks, examples, proofs, ...) then you can use the theorem package. Alternatively, the following sets up an environment `remark` whose content is in roman.

      \newtheorem{preremark}{Remark}
      \newenvironment{remark}%
        {\begin{preremark}\upshape}{\end{preremark}}

The ntheorem package provides roman theorems directly.

`ntheorem.sty`
  macros/latex/contrib/supported/ntheorem.tar.gz
`theorem.sty`
  Distributed as part of macros/latex/required/tools.tar.gz