The underline character in some fonts is heavier than the Underline
property. You may be able to get a narrower underline by underlining spaces
or a tab, or you could reduce the font size for the underline characters.
See http://word.mvps.org/FAQs/TblsFldsFms/LinesInForms.htm

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Suzanne S. Barnhill
Microsoft MVP (Word)
Words into Type
Fairhope, Alabama USA
Word MVP FAQ site: http://word.mvps.org
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> In making a form in Word 2000 that is to be filled in by hand, I used
> underlines for lines. The font is Arial Narrow 12. The text is not
> bolded, but the lines are too thick. Is there a way to reduce the
> thickness of the underline character?