The 3'-untranslated region (UTR) of the myelin basic protein (MBP) mRNA has been found previously to enhance the translational efficiency of the coding region by two-fold in cell-free translational systems. In this study, we transfected eukaryotic expression vectors containing the reporter cDNA for chloramphenicol acetyltransferase (CAT) with or without the mouse MBP cDNA 3'-UTR into cultured cells. CAT activity in the mouse oligodendrocyte cell line, N20.1, transfected with a CAT cDNA containing the MBP 3'-UTR [CAT-MBP 3'-UTR], was twice as high as that of the CAT cDNA without the 3'-UTR; CAT activities for the two constructs were the same in the mouse fibroblast cell line, NIH 3T3. Using reverse transcriptase PCR quantitative analysis, the expression of mRNA was determined. The level of the [CAT-MBP 3'-UTR] mRNA was about ten times higher than CAT mRNA in N20.1 cells but they were the same in NIH 3T3 cells. We conclude that the 3'-UTR of MBP gene increases gene expression at both the mRNA and protein levels in oligodrocyte cell lines, probably through a post-transcriptional mechanism such a message stabilization.