T(p) phase diagrams for the mesomorphic compoundstrans-4-n-butylcyclohexane-1-carboxylic acid 4-cyanophenyl ester (D4N),trans4-n-pentylcyclohexane-1-carboxylic acid 4-n-pentylphenyl ester (D55),trans-4,4′-di-n-propyl-1,1-bicyclohexyl-cis-4-carbonitrile (33CCN),trans-4-methoxy-4′-propyl-1,1′-bicyclohexane (3O1CCH) andtrans-4-methoxy-4′-n-butyl-1,1′-bicyclohexane (4O1CCH) are presented. The experiments were performed using high pressure microcomputer-assisted differential thermal analysis equipment in the temperature range 300 to 500 K up to a maximum pressure of 8 kbar. Some special high pressure effects for liquid crystals, such as pressure-induced or pressure-limited phases and changes from monotropic to enantiotropic polymorphism were observed. For the correlation of the experimental results, an extension of the Simon equation was used; one of the regression parameters of the clearing curve equation was found to be correlated with the molecular structure of the liquid crystal substances under test.