The polymerase chain reaction was used to amplify five variable regions of varicella zoster virus DNA from 20 samples of vesicle fluid. Two of the regions, R1 and R5, were found to be polymorphic, with the former having three alleles (A, B and C) and the latter, two (A and B). The R1 and R5 polymorphisms were stable up to passage five in tissue culture. The sensitivity of the PCR (down to six copies) enabled detection of virus from vesicle fluid dried on glass slides and overall the method was five times more sensitive than conventional tissue culture. The method described is simple, sensitive and informative and provides a means by which questions about the epidemiology and clinical biology of VZV infection may begin to be addressed.