eng Oriental Scientific Publishing Company Biosciences Biotechnology Research Asia 0973-1245 2017-06-28 14 2 793 799 10.13005/bbra/2510 24673 article Shibsankar Das 1 Department of Mathematics, Uluberia College, Uluberia, Howrah, West Bengal, India-711315. Genes expressed at higher level exhibit extreme codon bias towards the use of optimal set of codons and based on this hypothesis, several codon usage indices are used to predict gene expressions in different genomes. This study analyzed a codon usage methodology, MRCBS (Modified Relative Codon Bias Strength) to explicate the outlines of gene expression in the Nanoarchaeum equitans kin4-M genome. The analysis of this work revealed that most of the highly expressed genes of this genome involved in protein synthesis, DNA/protein metabolism, protein fate, cellular process, ribosomal / translation and transcription factor, amino acid biosynthesis and many hypothetical proteins. It is also observed that MRCBS correlates better with codon adaptation index than the other widely accepted codon bias measures. https://www.biotech-asia.org/vol14no2/analysis-of-gene-expression-using-modified-relative-codon-bias-strength-in-nanoarchaeum-equitans/ Codon bias index; codon bias; CAI (Codon Adaptation Index)GC content; predicted highly expressed genes;