A simple method which allows rapid, reproducible biotyping of Candida albicans isolates, and is suitable for use in any diagnostic medical microbiology laboratory is described. This system comprises three tests, the API ZYM system, the API 20C system, and a plate test for resistance to boric acid. The system differentiated a possible 234 biotypes, of which 33 were found amongst the 130 isolates of C. albicans taken from oral, genital and skin sites. Major biotypes found amongst oral and non-oral isolates were similar, although differences were found amongst minor biotypes. The new system was found to be reproducible, discriminatory, reasonably fast (48 h), easy to perform, and had no requirement for specialised equipment. Hence this biotyping system is suitable for use in diagnostic microbiology laboratories for epidemiological investigations of C. albicans infections.