Since 1976 the Department for Radiation Protection of the Austrian Research Centre Seibersdorf has been operating a TLD Personnel Monitoring Service, which presently covers about 18,000 radiation workers in Austria, with monthly monitoring periods. We have been the first accredited monitoring service in Europe, which fully converted from film dosimetry to TLD. From the beginning up to 1991 the service was based on three automated TLD systems Model 2271 from HARSHAW, USA. After extensive testing and comparisons, since almost four years now, the monitoring service has been operating on two HARSHAW 8800 systems, which are described in more detail below. (author).