An employee’s job performance does not necessarily decrease just because the employee gets older. But there is an anticipated correlation between reduced job performance and age with respect to certain job assignments. Along with an increased life expectancy in today’s society it’s important to promote equal opportunities regardless of age. The purpose of this thesis is to clarify under witch circumstances a dismissal due to insufficient work performance is justified. Furthermore this thesis purpose is to clarify how current legislation affects elderly’s position on the Swedish labour market when it comes to dismissal due to insufficient work performance. Even though Swedish and EU provision protect senior employees rights to some extent, there are still gaps in the legislation that can disfavour elderly´s possibilities to maintain their employment. In order to answer the research questions at issue a traditional legal dogmatic method is applied in combination with a sociological law perspective.