Hi Dixie,

If your search column for the 2nd workbook is also similar as "A" then try this code.

If it's a fixed column, however a different one than you can amend "1" to whatever you'd like under "ImportWB"

Paste in a new module

Option Explicit
Option Compare Text
Sub HighLightText()
Dim i As Integer, counter As Integer, ExportWb As Object, ImportWb As Object, lr As Range
i = 1
counter = 1
Set ExportWb = Workbooks("DB (Old App).xlsx").Sheets("DB (Old App)").Cells
Set ImportWb = Workbooks("Missing PI Tags 20141021b.xlsx").Sheets("Jacobs").Cells
Set lr = Workbooks("Missing PI Tags 20141021b.xlsx").Sheets("Jacobs").Cells(Rows.Count, 1).End(xlUp).Offset(1, 0)
Do While i < 501
Do While counter < lr.Row + 1
If ExportWb(i, 1).Value = ImportWb(counter, 1).Value Then
ImportWb(counter, 1).Interior.ColorIndex = 6
End If
counter = counter + 1
Loop
counter = 1
i = i + 1
Loop
MsgBox ("The task has been completed"), vbInformation
End Sub
If you want to search the entire sheet with all the columns then you can use John's Code.

Just try removing

Workbooks("Missing PI Tags 20141021b.xlsx").Sheets("Jacobs").Activate