For many decades this was the term used for a doctor or dentist in training for a hospital or GP career who had proceeded beyond the first stages of being a house officer. The term has now been replaced by ‘specialist trainee’ (ST) followed by the number of years in training – e.g. ST4, ST5 etc. It is likely, however, that both doctors and the public will continue to use the term ‘registrar’ for many years. After a period in this grade – usually 3–6 years – they may be appointed as GP principals or gain a certificate of specialist training (provided they have passed the appropriate higher examinations) and be able to apply for NHS consultant posts. In 2004 there were almost 55,000 specialist registrars in the UK and more than 5,000 GP registrars. Registrar numbers are also regulated by the government to achieve a balance between the numbers in training and the likely number of vacancies for career-grade doctors or dentists in the future.

The term is also used for a public official responsible for registering births, deaths, and marriages.