Erika,
Another idea. If you want the maximum values to be highlighted, use the
formulas suggested by various respondents to your question and get column C
conditionally formatted. Only the maximum values will be highlighted. (
Format Conditional formatting -- in the dialogue box that pops up select
"Formula is " and copy the formula you like and indicate the formatting you
want by pressing format button and selecting a color your choice.

"Erika" wrote:

I have a sample of the spreadsheet that I am working with below, what I need
to do is put together a function or formula that will flag the column with
the highest ODM reading for each unit. Any ideas on a way that I could do
that - once the row was flagged on could filter to get the report that I want
- each unit listed with only the highest ODM.

unit Miles ODM
1 10 50000
1 20 40000
3 100 10
3 150 150
3 200 250000