This review examines interactions between DNA and soil with an emphasis on the persistence and stability of DNA in soil. The role of DNA in genetic transformation in soil microorganisms will also be discussed. In addition, a postulated mechanism for stabilization and elongation/assembly of primitive genetic material and the role of soil particles, salt concentrations, temperature cycling and crystal formation is examined. Table 1. Examples of nucleic acids adsorption, activity and methods used to study soil microbial DNA. ADSORPTION 9 Clay-nucleic acids complexes 9 Adsorption of nucleic acids by montmorillonite 9 Degradation of nucleic acids in soil producing inorganic orthophosphate 9 DNA sorption to soils and sediments 9 Magnesium, calcium and manganese increased binding of bacterial DNA to sterile sediments 9 Preferential adsorption of small DNA fragments (2.69 kbp) to soils 9 Adsorption and desorpfion of DNA and degradation of adsorbed DNA on sand by DNase I 9 Adsorption of plasmid DNA to mineral surfaces and protection form DNase I activity 9 Protection of sediment-adsorbed transforming DNA from DNase inactivation EXTRACTION, PURIFICATION AND AMPLIFICATION OF DNA 9 DNA-content of soil bacteria of different cell size 9 Direct extraction, purification and amplification of DNA from soil, water and sediment 9 Direct extraction of DNA from soil 9 Direct extraction of DNA from forest soils 9 Direct extraction of DNA from rhizosphere 9 Determination of bacterial DNA in soil 9 DNA probing of soil bacterial communities GENE TRANSFER 9 Natural genetic transformation in soil 9 Transformation of B. subtilis by DNA adsorbed to sand 9 Transformation of B. subtilis by DNA adsorbed to montmorillonite 9 Bacterial conjugation in soil 9 Gene transfer in the environment 9 Gene exchange in Bacillus subtilis in soil