The package showframe makes the page margins visible and hence is a handy tool if you have problems with the document margins. It will display a box showing the margins as well as lines for the header and footer.
\usepackage{showframe}
If you only need to show margins for a particular page, use:
\usepackage[noframe]{showframe}
and at the page:
\AddToShipoutPicture*{\ShowFramePicture}
The geometry package offers similar functionality:
\usepackage[showframe]{geometry}
Simple and useful.
Also consider my post on margin notes.

April 20th, 2011 at 12:38 pm
Thanks for that info, that is very useful.
I have a document with a bleed of 0.125″. I’ve set my page to take this in consideration and I would like to print the bleed margin (so a line around the outside border of the page, 0.125″ from the side).
Do you know a package to do that?
April 25th, 2011 at 3:59 am
That may be helpful. Would you mind to post a minimal example, so I can see what you are doing.
Thanks, Tom.
May 13th, 2011 at 11:55 pm
I am using the showframe package, but I have different margins for the even and odd pages. Show frame works for the even pages, but the text bleeds into the right side margin on every odd page (the frame should be flipped over the y axis on the odd pages).
October 6th, 2011 at 5:32 pm
That high level info is no use to a non-technical person. The lines that indicated the margins just disappeared and now I can’t figure out how to get them back. already looked up reference books and the internet.
Any simple solutions????
Sincerely
scg
October 14th, 2011 at 5:59 am
Hi there,
One thing that sometimes helps is to delete any intermediate file generated while typesetting (*.aux, *.log, *.toc, etc.) and regenerate the document from scratch. Other than that, it’s hard to help without seeing what you are doing in your code. Please provide a minimal example and I’ll see what I can do…
Best, Tom.