An analysis of mRNA levels of 39 Cyp enzymes in the mouse brain and neuroblastoma cell lines, C-1300N18 and NB2a was performed using a real-time reverse transcriptase-polymerase chain reaction. Relative expression levels were quantified by normalized β-actin levels, and compared to the mRNA expression level of the cannabinoid receptor (CB1R), which is abundantly expressed in the mouse brain. Mean 2^-ddCts of CB1R in mouse brain, C-1300N18, and NB2a cells were 1.043, 1.003, and 1.005, respectively. Among Cyp mRNAs in the mouse brain, Cyp1b1 mRNA was the most abundantly expressed (2^-ddCt = 0.310), followed by Cyp46a1 mRNA (0.246). The other Cyp mRNAs moderately expressed (0.011 ~ 0.117) were Cyp1a1, 1a2, 2b10, 2c29, 2c50, 2d9, 2d10, 2d12, 2d22, 2d26, 3a11, 3a41, 4f14, 4f15, 4f16, and 4x1. On the other hand, 10 out of 39 Cyp mRNAs (Cyp 2b9, 2b13, 2b19, 2c37, 2c38, 2c55, 3a44, 4a12, 4a14, and 4f18) were not detectable (2^-ddCt < 0.001). In the neuroblastoma cell lines, C-1300N18 and NB2a, Cyp1b1 mRNA was also the most abundant and preferentially expressed, and relative expression levels to CB1R were 4.674 and 5.084, respectively. Thirteen other Cyp mRNAs (Cyp1a1, 1a2, 2a5, 2b10, 2c44, 2c50, 2c55, 2d10, 2d22, 3a11, 4f13, 4f15, and 4f16) were detected in the neuroblastoma cell lines, whereas 17 Cyp mRNAs (Cyp2c29, 2c37, 2c39, 2c40, 2d12, 2d34, 2e1, 3a16, 3a25, 3a41, 3a44, 4a10, 4a12, 4a14, 4f14, 4x1, and 46a1) were not under the current conditions. The pattern of Cyp mRNA expression was similar for both neuroblastoma cell lines. The present results provide fundamental and useful information on the significance of particular Cyp enzymes in the mouse brain and neuroblastoma cell lines, C-1300N18 and NB2a, which may be valuable tools for investigations on the neural expression and function of Cyp1b1.