The HDR 192Ir-Microselectron is a new high-dose-rate remote afterloading apparatus using a small 192Ir source with very high activity, 370 GBq (10 Ci). The size of the source permits treatment through catheters with diameters as small as 1.9 mm. This makes it possible to give endobronchial treatment to lung-cancer patients through a fibrebronchoscope in local anaesthesia. Preliminary results of treating cancer of the oesophagus, -prostate, -head and neck and breast cancers are promising. In addition the HDR 192Ir-Microselectron seems to have a promising potential in the treatment of several other tumours, especially in treating nonresectable intraabdominal tumours intraoperatively.