- Iain Grahame Rare Books - Specialist in rare natural history books, shooting books, stalking books, hunting books, fishing books, bird books and africana books and prints.
- Ice House Books - Second-hand and antiquarian books and publications; special interests include socialist, marxist and progressive fiction and non-fiction in English and other languages.
- Inlibris - Fine and rare books; specializes in autographs, manuscripts, and archives of significant personalities of science and the arts.
- Isis Antiquarian Books - Specialises in Philosophy, with books about art, history, religion and literature. Bilingual English and Dutch.
- The Ink Company - Rare and out of print books, sorted by specialty and searchable.
