Cell-mediated immunity, which includes interferon gamma (IFN-gamma) expression, is activated during the process of liver regeneration; however, the genetic pathway of this activation is still unclear. The present study evaluated variations in the interferon gamma receptor (IFN-gamma R) gene and its mRNA expression during liver regeneration after partial hepatectomy (PH). Male Wistar rats weighing approximately 200 g were subjected to PH (70 or 40%). IFN-gamma R gene expression in the remnant liver was measured by cDNA microarray, and mRNA expression was verified by real-time quantitative reverse transcription-polymerase chain reaction (Q-PCR) preoperatively and at 2, 4, 6, 12, 24, and 72 hours and 7 days postoperatively. The ratio of remnant liver weight to body weight increased markedly after 70 per cent PH and more gradually after 40 per cent PH. It reached near 90 per cent of the preoperative level at 72 hours after PH in both groups. The scanned spots of the genomic survey on the cDNA microarray chips were uneven and increased irregularly in number and density after PH. IFN-gamma R gene expression increased markedly in a single peak pattern, up to more than double the preoperative level, at 6 hours after 70 per cent PH. The curve in the 40 per cent PH group was flat and peaked at only 1.6 times the preoperative level. The variations in IFN-gamma R-related mRNA expression were verified by Q-PCR. Elevations in IFN-gamma R gene and mRNA expression were shown during the early stage of liver regeneration after PH. The genetic pathway of IFN-gamma/IFN-gamma R expression is activated during liver regeneration.