If it's a data validation dropdown list, you can't change the font size.
There are a couple of workarounds he

http://www.contextures.com/xlDataVal08.html#Font

If it's a combobox from the Control toolbox, you can change the font
size by switching to Design view, opening the Properties window, and
changing the Font properties.

If it's a combobox from the Forms toolbar, you can't change the font size.

hdaniels_uwco wrote:
How can I increase the size of the font in a drop-down list in Excel?


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Debra Dalgleish
Excel FAQ, Tips & Book List
http://www.contextures.com/tiptech.html