Within the framework of the electron-topological approach the structure-antagonist activity relationship was investigated in a series of dibenzo[a,d]cycloalkenimine derivatives. 71 Compounds were taken in the series. The conformational and quantum-chemical calculations were carried out for each compound. An activity feature revealed gave satisfactory description of the class of active compounds: two parameters, alpha(a) and P-a estimating the probabilities of its realization had values equal to 0.78 and 0.89, respectively. At the same time, regression analysis calculating Wiberg's indices, dipole moment and distance of two atoms for this activity feature, were performed. (C) 1997 Elsevier Science B.V.