A concern associated with the release of genetically engineered microorganisnls into soil is the persistence of recombinant DNA and its transfer to indigenous microorganisms. Persistence of a 630-bp DNA fragment of the chromosomally integrated Tn7-lac fusion element inserted into Pseudomonas aureofaciens Ps3732RN (Ps3732RNLll) was assessed in non-autoclaved and autoclaved sandy loam soil. PCR amplified 630-bp DNA bands, from DNA extracts of non-autoclaved soil in which log 8.1 killed P. aureofaciens Ps3732RNLll cells g^-1 dry soil were inoculated, were observed at 2 and 4 weeks after inoculation. DNA extracts of inoculated autoclaved soil subjected to PCR yielded the expected 630-bp DNA bands at 2, 4, 8, 12, 18 and 24 weeks after inoculation. The detection limit of PCR amplification was log 5.6 (4.1 x 10⁵) CFU g^-1 dry soil for killed cells. Results of this study demonstrate that extracellular genetically engineered DNA can persist in soil for extended periods of time.