Abstract: The present invention relates to pyrrolidine derivatives of the formula ##STR1## wherein R.sup.1 and R.sup.2 are defined as herein. The compounds are useful as anti-amnestic agent.

Abstract: Pyrrolidine derivatives having inhibitory action for proline-specific endopeptidase which are useful for anti-amnestic agent. The disclosed pyrrolidine derivatives as well as their acid addition salts can be administered orally or parenterally in the form of conventional pharmaceutical preparations. For instance, they can be administered orally in the form of conventional solid pharmaceutical preparations such as tablets, capsules, syrups and suspensions. Alternatively, they can be administered parenterally by injection in the form of conventional liquid pharmaceutical preparations such as solutions, emulsions, suspensions, etc. Also, they may be directly applied to rectum in the form of suppository. Further, the preparations may contain physiologically acceptable carriers, excipients, activators, binding agents, stabilizers, etc. In the case of injections, physiologically acceptable buffers, solubilizing agents or isotonic agents may be incorporated therein. Methods of production are also disclosed.