Spin column based genomic DNA preparation kits are designed for isolation of genomic DNA from whole blood, tissue culture cells, animal tissue, plant tissue, yeast, gram-positive and gram-negative bacteria. The spin column based method completely removes PCR inhibitors such as divalent cations and proteins. The obtained DNA is suitable for a variety of applications, including real-time PCR, southern blot analysis, genotyping and discovery or validation of SNP/SSR markers.