The melting transition of phospholipid-based microcylindrical tubules, has been investigated for single and multibilayer tubules, using high-field, high-resolution magnetic birefringence and precision microcalorimetry techniques. Measurements of the magnetically induced optical palarizability anisotropy and the heat capacity, reveal that the transition of multibilayer tubules is discontinuous, consistent with the melting behavior of crystalline lipid phases. Single bilayer tubules exhibit a melting transition that conforms with hexatic-smectic phase transitions.