The white rot fungus Pycnoporus cinnabarinus produces a characteristic phenoxazinone derivative red pigment, cinnabarinic acid (CA), which is formed by laccase-catalyzed oxidative dimerization from the precursor, an aminophenol, 3-hydroxyanthranilic acid (3-HAA) when glucose is the carbon source (Temp and Eggert, 1999; Eggert et al., 1995). Production of 3-HAA in P. cinnabarinus was completely inhibited by a combination of tryptophan and S(2-aminophenyl)-l-cysteine S,S-dioxide (APCD) while the fungus grew well and produced high amounts of laccase. The biosynthesis of 3-HAA is mainly through the metabolism of tryptophan in the kynurenine pathway. A minor pathway for 3-HAA synthesis is through the hydroxylation of anthranilic acid during the biosynthesis of tryptophan in the shikimic acid pathway (Kaichang et al., 2001). CA is active against several Gram-positive bacteria of the Streptococcus group (Liu, 2005). In this study, stimulation of cinnabarinic acid production by P. cinnabarinus in batch cultures was investigated for the possible industrial applications. Laccaseactivitywasdeterminedbymeasuring the oxidation of ABTS at 420nm. 3-HAA and CA was monitored with spectrophotometry, spectrofluorometry and LC–MS.