A protocol is described to enable the production of reliable genetic fingerprints of lichen-forming fungi using randomly amplified polymorphic DNA (RAPD) markers. Key features of the method are the use of mycobiont DNA extracted from axenic cultures by a phenol-chloroform procedure, and PCR amplification using DyNAzyme II DNA polymerase. RAPD-PCR fingerprints of Graphis scripta, G. elegans and Phacographis dendritica were successfully generated using this protocol and individual isolates could be identified on the basis of differences in banding patterns produced. DNA extracted from whole thalli of G. scripia was also subjected to RAPD-PCR but the fingerprints produced differed from those given by axenic cultures of the mycobiont. Therefore difficulties of interpretation may arise when whole thalli are used in RAPD analysis.