Since the discovery of microRNAs (miRNAs) their role has now been established in translational repression and gene silencing. In metazoans the miRNA target sites are in the three prime untranslated regions (3'UTR) of the mRNA. The function of miRNAs appears to be in gene regulation. Several miRNAs have been found to have links with some types of cancers, heart diseases, nervous system etc. In this book specific sites targeted by miRNAs in the 3′UTRs of mRNAs in the genome of C. briggsae were identified with the help of thermodynamic studies. RNAhybrid software was also utilized in the identification of miRNA targeted sites. This book could be helpful for students and teachers in the subjects of Molecular Biology, Genomics, Bioinformatics.