Abstract First principles calculations based on structures obtained by X-ray crystallography analysis are applied to identifying the intrinsic ferromagnetic nano-particle compound. We have found that this organic based nano-particle compound (EI236) exhibits anti-cancer property and, more important, possesses a magnetic property as it was readily attached to a magnet. EI236 exhibited intrinsic ferromagnetic behaviors from -268 celcius degree to 37 celsius degree and inhibited melanoma expansion in mouse tails when delivered to the melanoma lesion using a commercially available magnet. The local accumulation of the compound, as induced by the magnet, was readily visualized by magnetic resonance imaging (MRI) in mice. (n=4) Thus, EI236 acted as both an anti-cancer drug and an MRI contrast, and had pharmacological effects that could be delivered in a controlled manner. The identification of such compounds can overcome the long-standing problems of controlled drug delivery by magnetic force and may dramatically alter our concept of pharmacotherapy in the future, i.e., drug-targeting using a magnet and drug-dosing using MRI. Citation Format: Haruki Eguchi, Kunio Hirata, Reiko Kurotani, Hidenobu Fukumura, David J. Singh, Masahiro Yamamoto, Itaru Sato, Masanori Umemura, Masaki Yamamoto, Yoji Nagashima, Yoshihiro Ishikawa. Targeted drug delivery system and magnetic resonance imaging with intrinsic ferromagnetic nano-particle compound. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5570. doi:10.1158/1538-7445.AM2013-5570