Abstract: Objective Sialic acid and its derivatives in mammalian cells mainly include N-acetylneuraminic acid (Neu5Ac), N-glycolylneuraminic acid (Neu5Gc) and deaminoneuraminic acid (KDN), among which Neu5Ac can be catalyzed by cytidine monophospho-N-acetylneuraminic acid hydroxylase (CMAH) for the synthesis of Neu5Gc. In this study, the transcriptional level of CMAH in different tissues of BALB/ c mice were determined by relative fluorescence quantitative PCR, to provide a reference for further analysis of Neu5Gc levels in different tissues. Methods The mRNA sequence of CMAH was searched in the NCBI database and specific primers were designed. The mouse β-actin was selected as an internal control, and the transcriptional levels of CMAH in 9 different organ tissues of BALB/ c mice were detected by relative fluorescence quantitative PCR using SYBR Green dye. Results Among the 9 mouse organs, the transcriptional level of CMAH in the liver tissue was the highest, which was 2.46 times higher of that in the spleen, 3.17 times of the kidney, 5.14 times of the trachea, 11.70 times of the lung, 21.12 times of the myocardium, 31.37 times of the skeletal muscles, 66.90 times of the small intestine and 1056.99 times of the brain tissue, respectively. Conclusions CMAH is transcribed in many organ tissues of mice, and its transcriptional levels vary in a quite wide range.