Lenihan played four matches in the inaugural 1987 Rugby World Cup where he was the Irish captain and played three matches in the 1991 Rugby World Cup. The Munsterman captained his country 17 times (3rd highest of the amateur era, 7th all-time). He was selected for three British and Irish Lions tours - 1983, 1986 (IRB Centenary Match), 1989 - and captained the Lions on a number of occasions during their victorious tour of 1989. His 52nd and last Irish cap (6th highest of the amateur era) came against Wales on 18 January 1992.