Microsoft Office 2003 - Rotate Labels to Improve Chart Readability (Excel 2003)
There may be times when space limitations prevent Excel from displaying all of the category labels in a chart. Excel will try to compensate by displaying labels at an angel and will adjust the angle as you resize the chart. However, there may be times when you want to personally determine how the labels appear. Fortunately, it's easy to manually set the rotation angle. Note that this technique also works for value axis and data series labels.
First, double-click on the labels you want to change. When the appropriate Format dialog box appears, click on the Alignment tab. You can set a specific angle entering a number in the Degrees text box or by clicking in the Orientation preview box. Either of these actions will rotate the label controls; however, the text remains oriented horizontally within the control.