Rees toured with the British and Irish Lions to New Zealand in 1977, when he had yet to be capped by Wales, and South Africa in 1980 and at the time played club rugby for Neath. He made his international debut for the Lions against New Zealand at Eden Park, Auckland in August 1977 but had to wait until January 1979 for his first Wales cap, against Scotland at Murrayfield. Rees scored a try on his Welsh debut, and made his last appearance against France at the Parc des Princes in March 1983.