The study analyses the relations between Prussia and Russia in the field of dynastic politics and evaluates the role of kinship relations for the development of political cooperation in the period of diplomatic congresses before the Opava negotiations. It pays particular attention to the motives of both parties in the marriage between Grand Duke Nicholas and Princess Charlotte, describes specific diplomatic negotiations, and assesses the success of the influence of dynastic politics on the conservative, monarchist, and counterrevolutionary foreign policy orientations of Prussia and Russia in the first half of the 19th century.