Percutaneous transcatheter embolization is a commonly performed minimally invasive treatment used for a variety of clinical conditions. The goal of embolization is to occlude or decrease blood flow in arteries or veins. Each embolic agent has unique characteristics that make it more suitable in some medical indications and less in others. Embolic agents are classified on the basis of the duration of the occlusion as temporary or permanent. Permanent embolic agents are then subdivided into nonabsorbable microparticles, liquid agents, plugs and coils. Embolization coils are mechanical embolic agents which produce permanent vessel occlusion similar to surgical ligation. Steel coils are less expensive and are less likely to spontaneously migrate in highflow vessels. Platinum coils are expensive, malleable, and radiopaque. Bare metal coils may cause incomplete vessel occlusion, so most coils are coated with Dacron fibers making them thrombogenic. Pushable coils and injectable coils are most commonly used, user-friendly, quick, and inexpensive, but they cannot be easily retrieved once they are extruded from the catheter tip. Detachable coils are connected to a guidewire which allows them to be repositioned several times before release for precise placement, but they come with the disadvantage of higher procedure times and cost. A new generation of hydrogel coils swells in contact with blood which results in better aneurysm packing. A thorough knowledge of the properties of each embolic agent is required to ensure effective embolization. This thesis aims to evaluate which coil is best used in common medical indications which require embolization.