Yes. Select the sheet then click on Tools | Protection | Protect Sheet
and give it a password (twice - write it down to remember it as well).
You can also hide the worksheet (Format | Sheet | Hide), so it's not
obvious it is there.
However, bear in mind that Excel passwords are not very secure and can
easily be broken by someone who is determined.
Thanks for replies.
It probably wont help as I have to protect the workbook for the person I am
doing it for to stop her messing it up (nightmare)
There is just one sheet that she might not want her staff to see But if she
is allowed to protect/unprotect the workbook she will screw it up in 5
minutes.
I will just advise her to hide the sheet concerned (Its not life threatening
if the staff do access it)