Pseudomonas aeruginosa ATCC 17933 is able to oxidize ethanol to acetate under aerobic conditions. The P. aeruginosa acetyl-CoA synthetase (ACS) gene acsA was previously identified, and the ACS enzyme described to be required for growth on ethanol as the sole source of carbon and energy. Here, we investigated the transcriptional regulation of the acsA gene using an acsA::lacZ fusion. Transcription of acsA was regulated by the carbon source, and expression was maximal on ethanol, acetate and propionate. In addition, the induction depended on the response regulator ErdR, which also regulates hierarchically arranged genes for ethanol oxidation. Transcription of the acsA gene was repressed by addition of succinate to an ethanol-containing medium. This repression required Crc, the product of the catabolite repression control gene crc.