International conventions, as well as the Turkish legislation have brought provisions on equal treatment and non-discrimination, and in particular the recent Law on the Turkish Human Rights and Equality Institution. A distinction is to be made between the principles of “non-discrimination” and “equal treatment”. The prohibition of discrimination is to be complied at the beginning, duration and ending of employment; whereas equal treatment concerns relations during employment and in a certain measure the termination of employment. The duty of equal treatment has then to be examined more closely in cases of termination for just or valid causes, where some distinctions are to be made. The main issue is to define at which extent the employer has to comply with the principle of equal treatment when dismissals are due to just or valid causes, and especially for those having participated in a collective action. An assessment and synthesis of some recent court decisions and the legal consequences conclude this study.