Recently, chlorophyll-related compounds, pheophytin a and b have been identified as antigenotoxic substances in the non-polyphenolic fraction of green tea leaves, which suppressed umu C gene expression in tester bacteria induced by various genotoxic substances (Okai and Higashi-Okai, Cancer Lett., 107 : 117-123, 1997). To study the anti-inflammatory activity of these pigments, the authors analyzed the inhibitory effects of pheophytin a and b from green tea against functional activation of human polymorphonuclear neutrophils (PMNs) using in vitro cell culture experiments. (i) Pheophytin a and b from green tea caused a significant suppression against the opsonized zymosan-induced chemiluminescence in human PMNs in a dose-dependent fashion. (ii) Pheophytin a and b also exhibited suppressive effects on the release of an inflammatory cytokine, interleukin-1 beta from human PMNs stimulated by E. coli lipopolysaccharide. (iii) Pheophytin a and b showed a significant suppression against Formyl-Met-Leu-Phe (FMLP)-induced chemotaxis of human PMNs in a dose-dependent manner in Boyden＇s chamber experiment. These results suggest that pheophytin a and b from non-polyphenolic fraction of green tea have potent suppressive activities against the activation of human PMNs associated with inflammatory reactions.