While examining the taste of various proteins, we found that hen egg-white lysozyme, a bacteriolytic enzyme, had sweetness. Lysozymes from other sources such as turkey and soft-shelled turtle also showed sweetness with different tastes, heavy or light. In contrast, human lysozyme was tasteless. The amino acid sequences of the various lysozymes were similar to that of hen lysozyme, but hen lysozyme did not show significant homology to sweet proteins.