Drought is one of the major limitations to the food production worldwide and is endemic particularly in the semi-arid tropics. As a semi-aquatic plant species, originated from the tropical swamps, rice is very sensitive to drought. To survive drought situation plants also have evolved various adaptive mechanisms by changing its genomic sequences or by epigenetic modifications of specific genomic sequences by different kind epigenetic marks. These epigenetic marks plays important role in identifying and isolation of environment sensitive genes. The DNA cytosine methylation is the most important and most explored epigenetic system. For the purpose of finding drought responsive methylation sites and associated genomic regions involved, we have explained and used a very reliable and robust method called Methylation Sensitive Amplification Polymorphism (MSAP). We found this technique very useful for clearly differentiating drought tolerant genotypes from drought susceptible genotypes and isolating genes which are environmentally influenced. Hence, in future this book can be very helpful for breeders and researchers in improving crops for biotic and abiotic stresses.