His début concert took place at Carnegie Hall in New York in 1980. He has toured widely since then, giving concerts throughout Europe, the USA, and the Middle and Far East. Lethiec has served as a soloist with many leading European orchestras, and has worked with renowned chamber music ensembles.
He is a member of the Trio à vent de Paris together with Vincent Lucas and Philippe Hanon. He is an enthusiastic interpreter of contemporary music who has also recorded extensively, for example recently recording the world premiere of the three concertos of Penderecki and a CD dedicated to chamber music by the same composer.
Lethiec is a respected educator who teaches at the Paris and Nice Conservatories, regularly holds master classes at major educational institutions abroad, and is a visiting jury member at many international clarinet competitions. He is also Artistic Director of the prestigious Pablo Casals Festival in Prades, France.