Pyrrolnitrin (III, Fig. l), 3-chloro-4-(2-nitro-3-chlorophenyl)pyrrole, is a potent antifungal compound first isolated from Pseudomonas pyrrociniu. It was subsequently found that a number of Pseudomonads form pyrrolnitrin as a product of tryptophan metabolism. Other less active phenylpyrroles were also produced by this metabolic pathway; these include aminopyrrolnitrin (II), 2-chloropyrrolnitrin (III), isopyrrolnitrin [2,3-dichloro-4-(2-nitrophenyl)pyrrole], and oxypyrrolnitrin [3 chloro-4-(2-nitro-3-chloro-6-hydroxyphenyl)pyrrole]. Gas chromatography and thin-layer chromatographic (TLC) techniques have been used to analyze for these phenylpyrroles from Pseudomonads. A strain of Pseudomonas cepacia, isolated from apple leaves, inhibited the growth of Botrytis cinerea and Penicillium expansum on apples and pears, and was found to produce pyrrolnitrin. We have isolated other phenylpyrroles from P. cepacia, including compounds II and V. In addition, we found 3-(2-amino-3-chlorophenyl)pyrrole (I), previously isolated from a Pseudomonad grown in the presence of 7-chlorotryptophan, and 2,3-dichloro-4-(2-amino-3-chlorophenyl)pyrrole (IV), not reported previously. A high-performance liquid chromatographic (HPLC) method was developed for the separation and quantitative analysis of these five phenylpyrroles in P. cepacia fermentations.