Recently, stable isotope labeling by amino acids in cell culture (SILAC) has become an essential technique for quantitative proteomics, enabling us to comprehensively compare the protein expression changes in different states of cells. However, several limitations have arisen from the conventional SILAC method with respect to the requirement of using dialyzed serum, quantification of unlabeled cells, and arginine-to-proline conversion. To overcome these limitations, we introduced a dual labeling SILAC approach, which does not require dialysis of serum. Here, we review the principle and the features of our SILAC method as well as its application to quantitative proteomics.