This paper approaches simultaneous interpretation from a neurolinguistical and neuropsychological angle. Several related studies described in the present paper show 1) the existence of neural systems for translating from L1 to L2 and from L2 to L1, which are independent of language comprehension and production systems; 2) the activation of both cerebral hemispheres during simultaneous interpretation; and 3) the absence of the usual right-ear advantage in the processing of verbal material due to the interpreters' general habit of listening to the incoming message with one ear only for the purpose of controlling their own output with the other ear.