With this method: Dim f As Aspose.cells.FileFormatInfo = Aspose.cells.FileFormatUtil.DetectFileFormat("really_old.xls") I am able to detect f.FileFormatType = FileFormatType.Excel95 I realize your product inf…...Detecting old excel file formats Aspose.Cells Product Family Jeff_B October...Dim f As Aspose.Cells.FileFormatInfo = Aspose.Cells.FileFormatUtil...