Synthesis and physicochemical properties of new N-pyridyl derivatives of 3-phenyl and 3,3-diphenylsuccinimides (1-12) have been described. The obtained compounds were evaluated in respect of their anticonvulsant activity. The N-pyridyl derivatives of 3-phenylsuccinimides (7-12) abolished the protection against MES- and scMET-induced seizures, whereas N-pyridyl derivatives of 3,3-diphenylsuccinimides (1-6) were inactive. After molecular modelling and quantum-chemistry calculations the theoretical activity test was applied (W. Kwiatkowski, J. Karolak-Wojciechowska, SAR and QSAR Envir. Res. 1 (1993) 233; Chem. Abstr. 120, 153001 (1994). J. Karolak-Wojciechowska, M. Blaszczyk, W. Kwiatkowski, J. Obniska, A. Zejc, J. Chem. Cryst. 27 (1997) 297; Chem. Abstr. 127, 277834k (1997)). The molecular electrostatic potential (MEP) of the active compounds differed significantly from that of the inactive ones.