A Guglielmi Detachable Coil, or GDC, is a platinum coil commonly used in intracranial non-invasive surgery , for the occlusion of brain aneurysms. It was invented by Italian neurosurgeon Dr. Guido Guglielmi in 1990, and was gradually introduced in the later 1990s as an alternative to surgical clipping, which requires invasive surgery.

The peculiarities of this coil lie in its physical as well as its electrolytical properties: The material has a high memory effect, allowing it to easily bend and take its common coil shape. It is also highly sensitive to low currents, which allow the GDC to detach from the catheter that carries it, thus receiving the name of "detachable coil".

The long-term survival rates of patients treated with GDC's have shown to be higher relative to patients treated with surgical clipping. However, very short-term survival rates depend highly on if the GDC has managed to fully occlude the aneurysm.