In the rst edition of this book, we provided detailed protocols for fabricating oligonucleotide microarrays for mutational analysis [1]. Here, in the second edition, we provide (i) improved protocols developed during the last three years; and (ii) protocols for multiple sample hybridization with competitive deoxyribonucleic acid (DNA) hybridization (CDH) along with single sample hybridization. The information provided in this chapter should allow researchers to choose between single and multiple sample hybridization with CDH.