His collections of poems include:
- Poems (London, Cresset, 1958);
- Collected Poems, 1950-73 (Dublin, New Writers Press, 1973);
- Reductionist Poem (Dublin, Raven Arts Press, 1980);
- 41 Sonnet Poems (Raven Arts Press, 1982);
- RMS Titanic (Raven Arts Press, 1981);
- New and Selected Poems (Raven Arts Press/Manchester, Carcanet, 1982);
- The End of the Modern World (1989);
- Relationships (Dublin, New Island Press, 1992); and
- Minotaur (New Island Books, 1999).
Novels:
- The Life of Riley (Knopf, 1964).
Literary Criticism:
- No Laughing Matter: The Life and Times of Flann O'Brien. New Island Books, 2003. ISBN 1-904301-37-1
Memoirs:
- Dead as Doornails (Dublin, Dolmen Press, 1976)
- Essay on Patrick Swift:Veronica Jane O’Mara (ed.), PS...of course- Patrick Swift 1927-83, with contributions on Swift by George Barker, Anthony Cronin, Patrick Kavanagh, John McGahern, John Ryan , C. H. Sisson, Katherine Swift, David Wright(Gandon Editions, Kinsale, 1993)
Biography:
- Samuel Beckett: The Last Modernist (HarperCollins, 1996)