Of the vast array of prokaryotes on earth, only few (less than 1%) can be isolated on artificial laboratory media. This has greatly hampered our knowledge about such prokaryotes. These uncultivable species are important because they may yield many novel enzymes and catalysts with industrial applications such as antibiotics. The inability to grow and isolate these microbes has led to the emergence of a new technique viz. Metagenomics i.e. the culture-independent analysis of a mixture of microbial genomes. It differs from conventional methods as it deals with analysis of microbial DNA extracted directly from environmental samples. Due to the fact that 99% of prokaryotes are uncultivable, the possibility of discovery of novel enzymes is enormous and invaluable contributions to evolutionary biology, medicine and agricultural science can be expected from this newly developed technique in forthcoming years.