This paper considers the use computers in the radiological protection systems on the Joint European Torus (JET) experiment at Abingdon in the UK. JET is the largest fusion experiment in Europe. It uses a sophisticated computerised control system and the radiological protection systems are integrated into the overall control structure. The main protection systems are a radiation monitoring system for the JET buildings and an access control system. The access control system includes a facility for recording the radiation doses incurred on each visit to a controlled area.