Multi-modal　imaging　agents　are　desirable　for　tumor　diagnosis　because　they　can　provide　more　information　on　the　tumor　than　single-modal　imaging　agents.　However,　most　reported　multi-modal　imaging　agents　are　dual-modal　agents　rather　than　tri-modal　agents;　therefore,　detailed　information　on　the　tumor　may　still　be　insufficient　when　such　imaging　agents　are　used.　To　ameliorate　this　issue,　we　synthesized　a　tri-modal　imaging　agent,　composed　of　gold　cluster　and　gadolinium　oxide　integrated　nanoparticles　(denoted　as　AuGds)　using　bovine　serum　albumin　(BSA)　as　the　template　via　a　bio-mineralization　method.　The　AuGds　exhibit　red　fluorescence　at　similar　to　660　nm　for　optical　imaging,　strong　X-ray　absorption　(around　700　HU)　for　CT　imaging,　and　a　high　r(1)　value　(similar　to　12.39　mM(-1)　s(-1))　for　MR　imaging.　After　being　chemically　modified　with　folic　acid　(FA),　the　AuGds　can　specifically　target　folate　receptors　on　KB　tumor　cells,　and　permit　in　vivo　optical,　MR,　and　CT　imaging　of　xenografted　tumors.　By　comparing　these　three　imaging　modalities,　very　clear　structural　and　anatomical　information　on　the　in　vivo　tumor　can　be　obtained.　The　AuGds　show　good　biocompatibility,　quick　renal　clearance,　and　do　not　induce　normal　tissue　toxicity　in　vivo.