Lastrow is an integervalue, so you just calcualte that from the row property, you don't also select (none of the code I have given you selects it). You then pass that variable to the Rows object

[vba]Sub BoldLastRow()
'Bold last row
Dim Lastrow As Long

Lastrow = .Cells(.Rows.Count, "A").End(xlUp).Row
Rows(Lastrow).Font.Bold = True

End Sub[/vba]


BTW, the tags are vba and /vba within brackets