ATP-sensitive potassium (KATP) channels are expressed in multiple tissues, where they provide a link between cellular metabolism and membrane excitability. They consist of two subunits: the inward rectifier potassium channel Kir6, which forms the pore, and the sulfonylurea receptor SUR, an ATP-Binding Cassette (ABC) transporter that functions as the regulatory subunit. Differential expression of Kir6 and SUR isotypes leads to formation of KATP channels with distinct electrophysiological and pharmacological properties, and a number of tissue-specific subunit combinations have been described. Although KATP channels in the liver remain largely unexplored, there is some evidence that KATP channels are expressed in hepatocytes. However, a rigorous characterization of the subunit composition of hepatocytic KATP channels is still lacking. In order to address this, we performed end-point RT-PCR for KATP channel subunit mRNA in extracts from mouse and rat liver, as well as from the human-derived hepatocyte cell line HepG2. Interestingly, a range of expression patterns was observed. In mouse liver, Kir6.1 and SUR2 were detected, while no signal was seen for Kir6.2 and SUR1 (n=3-5). In rat liver, signal was detected for all major subunits: Kir6.1, Kir6.2, SUR1, SUR2A, and SUR2B (n=3). In HepG2 cells, signal was detected for Kir6.1, Kir6.2, and SUR2B, but not for SUR1 or SUR2A (n=3). While detection of Kir6.1 and SUR2/SUR2B in mouse and rat liver may reflect vascular smooth muscle channels, the presence of these subunits in HepG2 cells indicates that they may in fact represent KATP channels expressed in hepatocytes. Additionally, expression of Kir6.2 in both rat liver and HepG2 cells is suggestive of a Kir6.2-containing hepatocytic KATP channel. Ultimately, correlation with electrophysiological and pharmacological experiments will be necessary to elucidate the subunit composition of hepatocytic KATP channels, as well as their physiological role.