It is Shown that the empirical eigenvalue distribution of suitably distribu
ted random unitary matrices satisfies the large deviation principle as the
matrix size goes to infinity. The primary term of the rate function is the
logarithmic energy (or the minus sign of Voiculescu's free entropy). Exampl
es of random unitaries are also discussed, one of them is related to the wo
rk of Gross and Witten in quantum physics. (C) 2000 Editions scientifiques
et medicales Elsevier SAS.