Mechanisms are provided for relational context sensitive anonymization of data. A request for data is received that specifies a relational context corresponding to a selected group of selected persons selected from a global group of persons based on the relational context. The relational context specifies one or more attributes of selected persons in the selected group that establishes a relationship between the selected persons and distinguishes the selected persons from non-selected persons in the global group that are not in the selected group. For the relational context, based on a corpus of personal information data corresponding to the selected persons, key attributes in the personal information data are determined and a rarity value for each key attribute is determined. Selected key attributes are then anonymized based on the determined rarity value for each of the key attributes within the relational context of the selected group.