Retirement is a critical concern as well as a critical event in the working life of every employee of a formal organization. The retirement age is a major aspect of management of employee retirement. Hardly research studies carried out to give an informative analysis which has both theoretical and practical importance are found, particularly in Sri Lanka which recently experienced a change of the retirement age, in fact an increase. This conceptual research paper was written to give answers for eleven research questions formulated with regard to the phenomenon of retirement age. The research questions were answered by adopting a desk research strategy. It was revealed that a retirement age exists for any permanent employment, it is important due to several valid reasons, it has a form called mandatory retirement age which is different from the minimum retirement age, mandatory retirement age exists owing to accepted reasons, it has a case against itself and a case in faour of itself, a universally accepted retirement age does not exist owing to some reasons, there is a possibility of extending the retirement age with certain pons and cons, and a good organization can determine appropriate retirement ages.