Communication: Substituted porphyrins with enhanced discotic behavior are reported. It is shown that suitably substituted 5,10,15,20-tetraarylethynylporphyrins behave as columnar discotic mesogens, preliminary studies indicating their potential as third-order nonlinearly optically active materials. The synthesis of the compounds is described and their characterization by mass spectrometry, UV-vis, H-1-NMR, and IR spectroscopy, and microanalysis discussed. Thermal data on the three discotic mesogenic porphyrins are presented.