We have compared PC12 cell lines derived from different laboratories and the newly developed mouse pheochromocytoma (MPC) cell line. Morphologically, there were distinct differences in size, shape, adherence, and clumping behavior, which varied in response to different culture media, growth substrates, and nerve growth factor. Quantitative messenger ribonucleic acid (mRNA) analysis showed significant variability in the expression of the catecholaminergic biosynthetic enzymes tyrosine hydroxylase (TH), phenylethanolamine N-methyltransferase (PNMT), the noradrenaline transporter (NAT), and neuron-specific enolase (NSE) between all lines examined. Of most significance were the increased levels of PNMT mRNA in the MPC cells, which were to 15-fold greater than in the PC12 cell lines grown under the same conditions in Dulbecco modified Eagle medium (P ≤ 0.05). Growth of MPC cells in Roswell Park Memorial Institute media induced a further significant increase in PNMT gene expression (P ≤ 0.05). Immunohistochemistry for TH, PNMT, and NAT was generally consistent with mRNA analysis, with the MPC cells demonstrating strong immunoreactivity for PNMT. The MPC cells showed the highest levels of desipramine-sensitive [³H] noradrenaline uptake activity (threefold > than PC12 American Type Culture Center line, P ≤ 0.05), despite relatively low levels of NAT mRNA. These results indicate that PC12 cell lines should be carefully chosen for optimal utility in the study of chromaffin cell or sympathetic neuron biology and that cell features will be influenced by type of media and substrate chosen. Furthermore, they confirm that the new MPC cell line is likely a useful model for the study of adrenergic mechanisms or studies involving NAT.