One way ..

Suppose the list to be entered is in col F

Select col F

Click Data Validation

Make the settings:
Choose under "Allow:" : Custom
Source: =COUNTIF($F$1:F1,F1)<=1

Click OK

--
Rgds
Max
xl 97
---
GMT+8, 1° 22' N 103° 45' E
xdemechanik <atyahoo<dotcom
----
"Jim K" <Jim wrote in message
...
I am inputing a large column of names and numbers and would like to insure
I
don't repeat any. I'm not sure how the Vlookup works I continually
receive
errors and the If command only works with 2 cells. Thank you in advance
for
any help!!