Complexation selectivity curves were obtained by theoretical conformational analysis and penalty functions in terms of the conformational factors in the following crown ethers: 15-crown-5; benzo-15-crown-5: 18-crown-6; benzo-18-crown-6; dibenzo-18-crown-6; cyclohexano-18-crown-6. In the last case the effect of cis—trans isomerism in the bridging bonds on the selectivity of complexation with the ligand was investigated. Analysis of the selectivity curves shows that the introduction of aromatic fragments into the macrocycle reduces its adaptive capabilities. The complexation selectivity of the ligands from the selectivity curves is compared with the experimental stability series of the crown ether complexes with alkali metal