A nested PCR has been developed to detect Bacillus anthracis spores in natural soil and waste samples which may be heavily contaminated by organic and inorganic compounds as is the case at former tannery sites. Outer and inner pairs of primers were designed from the protective antigen gene of the plasmid pX01 as well as from the genes B and C of the capsule region of the plasmid pX02. The DNA was prepared from an enrichment broth after killing the vegetative cells by H2O2 treatment. The method allows the detection of less than 10 spores per 100 g of the original soil sample. This is between 10(4)-fold and 10(7)-fold more sensitive than the conventional culture diagnosis.