PCR stands for polymerase chain reaction. It was invented to amplify specific regions of a DNA strand in tissues, resulting in the tremendous development in biochemical and molecular biological fields. Nowadays, the PCR method is also quite available in inner ear researches as modified versions, because it needs just small amounts of samples in inner ear tissues. The modified versions are as follows: reverse transcription (RT)-PCR, real-time quantitative PCR, in situ PCR, DNA subtraction, DNA microarray, single nucleotide polymorphism (SNP) analysis for using mRNA and reporter gene assay, gel mobility assay for using genomic DNA. Here in this paper, we would like to introduce the PCR method from original to modified in our inner ear biological field.