The relationships between mathematics, mathematics education and issues such as social justice and equity have been addressed by the sociopolitical tradition in mathematics education. Others have introduced explicit discussion of ethics, advocating for its centrality. However, this is an area that is still under developed. There is a need for an ethics of mathematics education that can inform moment to moment choices to address a wide range of ethical situations. I argue that mathematics educators make ethical choices which are necessarily ambiguous and complex. This is illustrated with examples from practice. The concept of ethical dimension is introduced as a heuristic to consider the awareness of different forms of relationship and arenas of action. A framework is proposed and discussed of four important dimensions: the relationship with others, the societal and cultural, the ecological and the relationship with self. Attending to the different ethical dimensions supports the development of a plural relational ethics. Navigating ethical complexity requires embracing diverse and changing commitments. An ethics that takes account of these different dimensions supports an ethical praxis that is based on principles of flexibility and a dialogical relationship to the world and practice.