Stabilization and destabilization of liquid crystalline phases in mixtures of derivatives of phenol and cyclohexanole with pyrrolidines and pyridines were investigated by phase diagrams. Whereas in mixtures with pyrrolidines a strong destabilization of the liquid crystalline state was found, mixtures with pyridines stabilize LC phases. The results are interpreted by 1:1 associates formed by hydrogen bridges and the molecular shape of these complexes.