Novel 3-mono-, 3,4-di- and 3,4,4,-tri-substituted pyrrolidine compounds, these compounds for use in the diagnostic and therapeutic treatment of a warm-blooded animal, especially for the treatment of a disease (=disorder) that depends on inappropriate activity of renin; the use of a compound of that class for the preparation of a pharmaceutical formulation for the treatment of a disease that depends on inappropriate activity of renin; the use of a compound of that class in the treatment of a disease that depends on inappropriate activity of renin; pharmaceutical formulations comprising a said substituted pyrrolidine compound, and/or a method of treatment comprising administering a said substituted pyrrolidine compound, a method for the manufacture of said substituted pyrrolidine compounds, and novel intermediates and partial steps for their synthesis are described. The substituted pyrrolidine compounds are especially of the formula I ##STR00001## wherein the substituents are as described in the specification.