Production of a novel antimicrobial tropolone, beta -thujaplicin, in Cupressus lusitanica suspension cultures was studied by using a variety of chemicals and fungal elicitors. Sodium al,alginate, chitin, and methyl jasmonate resulted in 2-, 2.5-, and 3-fold higher beta -thujaplicin production, respectively, than in the control. Significantly improved beta -thujaplicin production (187 mg 1(-1)) was obtained using a high cell density (180-200 g 1(-1)) and fungal elicitor treatment [10 mg (g fresh cells)(-1)] in a production medium with a high ferrous ion concentration (0.3 mM). This improved volumetric productivity was 3-to 4-fold higher than obtained under standard conditions. A synergistic effect of fungal elicitor and ferrous ion on beta -thujaplicin production was also suggested by our study. Plant cell culture technology is a promising alternative for producing a large variety of secondary metabolites that are widely used as food additives, pharmaceuticals, and dairy products (Verpoorte et al. 1999). Thus, beta -thujaplicin production by plant cell cultures was developed with the goal of commercial application (Berlin and Witte 1988; Itose and Sakai 1997; Ono et al. 1998). However, the production of beta -thujaplicin by plant cell cultures is still not competitive for use in industrial applications. In this study, we assessed the effects of methyl jasmonate, alginate, chitin, and fungal elicitor on beta -thujaplicin production; we obtained a significantly elevated beta -thujaplicin production by using an improved culture strategy.