Analogical proportions are statements of the form “x is to y as z is to t”, where x, y, z, t are items of the same nature, or not. In this paper, we more particularly consider “relational proportions” of the form “object A has the same relationship with attribute a as object B with attribute b”. We provide a formal definition for relational proportions, and investigate how they can be extracted from a formal context, in the setting of formal concept analysis.