Intermediate filament Nestin is a marker of neural precursor cells. Its expression pattern during mouse brain development was studied in the present investigation. A pair of primers based on the sequence of mouse Nestin were found best to be suit for the reverse transcriptional PCR (RT-PCR) with this pair of Nestin Primer. Using RT-PCR, Nestin transcripts were detected during the development of the central nervous system (CNS) of mouse, from embryonic day 10 to adult brain. We found that the Nestin showed a transient expression in the development of cerebrum. At the embryonic day 14, the expression of Nestin mRNA reached the highest peak, and was then down-regulated. In the postnatal cerebellum, Nestin gene was also expressed in a transient pattern. The highest peak of Nestin mRNA expression emerged at postnatal day 5, and was then down-regulated. Nestin mRNA expression in 10 kinds of adult mouse tissues did not yield any positive results.