The tricarboxylate carrier (TCC), an integral protein of the mitochondrial inner membrane, transports mitochondrial acetyl-CoA into the cytosol, where lipogenesis occurs. We investigated in rat liver mitochondria the effect of diets enriched with saturated fatty acids (beef tallow, BT), monounsaturated fatty acids (olive oil, OO) or n − 3 polyunsaturated fatty acids (fish oil, FO), respectively, on the activity and expression of TCC. TCC activity decreased, in parallel with TCC mRNA abundance, only upon FO-feeding. The TCC transcription rate, mRNA turnover and RNA processing indicated that FO administration regulates TCC gene at transcriptional and post-transcriptional steps, whereas BT- and OO-feeding do not seem to affect either TCC activity or gene expression.