Utilization of the hydroaromatic compounds, quinate and shikimate, by Corynebacterium glutamicum was investigated. C. glutamicum grew well on either quinate or shikimate as sole carbon sources. Disruption of qsuD encoding quinate/shikimate dehydrogenase completely suppressed growth on either substrate, but did not affect growth on glucose, indicating that the enzyme encoded by qsuD catalyzes the first step of catabolism of quinate/shikimate, but is not involved in the shikimate pathway required for biosynthesis of various aromatic compounds. On the chromosome of C. glutamicum, the qsuD gene is located in a gene cluster also containing qsuA, qsuB and qsuC genes, which are probably involved in the quinate/shikimate utilization pathway to form protocatechuate. RT-PCR analyses revealed that expression of the qsuABCD genes was markedly induced during growth on either quinate or shikimate relative to expression during growth on glucose. The induction level by shikimate was significantly decreased by disruption of qsuR, which is located immediately upstream of qsuA in the opposite direction, and encodes a LysR-type transcriptional regulator, suggesting that QsuR acts as an activator of the qsuABCD genes. The high induction of qsuABCD genes by shikimate was still observed in the presence of glucose, and simultaneous consumption of glucose and shikimate during growth was observed.