In tomato (Lycopersicon esculentum L. cv. UC82b) two distinct genes (designated LeCS1 and LeCS2) code for chorismate synthase. The corresponding cDNAs have been isolated and characterized. The deduced amino acid sequences are 88% identical. Both genes encode chorismate synthases with putative plastid-specific N-terminal transit peptides. The two genes are predominantly expressed in flowers and roots and, to a lesser extent, in stems, leaves, and cotyledons, but the steady-state levels of LeCS1-specific transcripts are consistently higher than those of the LeCS2-specific transcripts.