>Thanks for the answer anyway, but I didn't mean labels in the forms.
>My problem is that I want to create a report in which text boxes can be rotated by 90 °.
>Could you help me anyway ?

You can apply the same idea:
Box expression: substr(table1.field1,1,1)+chr(13)+substr(table1.field1,2,1)+....
and check 'Stretch with Overflow'