On the occasion of the centenary of the first use of an iodinated contrast agent (Lipiodol®) in 1921, this review traces the history of contrast agents that have closely accompanied the innovation of radiology equipment. Lipiodol is an iodinated oil that has made it possible to highlight the interest of the visualization of closed structures of the body (e.g., lung, subarachnoid space, bladder, and joints) and blood and lymphatic vessels. Other water-soluble products then appeared with a radical change in 1953 with the marketing of diatrizoate. The appearance of computed tomography scanners was concomitant with that of low osmolality iodinated contrast products. The arrival of magnetic resonance imaging was quickly followed by gadolinium complexes and then superparamagnetic particles based on iron oxide particles. Thus, the landscape has changed in recent years in radiology, with imaging taking the lead in the current diagnostic scheme.