Montmorillonite (Mt) can be used as a simultaneous medical imaging and drug delivery agent for transcatheter arterial embolization. In this technique, the arterial vessels around tumors are blocked by drug loaded micro-sized Mt particles so oxygen and nutrition from the blood flow are blocked and drugs are released by the particles into the tumor site. Both devascularization (achieved by cutting off the oxygen and the nutrition) and drug release around tumor site can result in the progressive shrinkage of the tumor size. Mt is highly applicable and unique for transcatheter arterial embolization due to the size, adsorption capability, and biocompatibility of the particles. Mt has been considered previously as a targeted drug delivery agent to the gastrointestinal tract only for oral applications due to its slow and sustained drug releasing properties, but it has not yet been investigated as a targeted drug delivery agent for tumors at different or highly-specific areas. In this study, interactions of purified montmorillonite (PMt) with a cone beam computer tomography (CT) contrast material and an antitumor drug were investigated to prepare drug releasing arterial embolic clay mineral particles that enable medical imaging. In-vitro studies were carried out to show the biocompatibility of PMt The swelling and adsorption properties of PMt in the presence of the CT contrast material or antitumor drug were investigated to find a proper concentration for possible embolization. The results show that both the CT contrast material and antitumor drug could penetrate to the interlayer spaces and were adsorbed by the surfaces of the PMt particles. The size of the PMt increased due to both the adsorption and coagulation, which made the particles suitable for the arterial embolization procedure where a specific particle size is required to successfully obtain embolization. In-vivo tests of PMt as a CT contrast carrier and in-vitro drug activity on MCF-7 (human breast adenocarcinoma) cells were also satisfactory using the prepared embolic PMt particles.