A polyamide suture includes an elongate core formed of multiple twisted and heat set filaments formed of a first polyamide material and a sheath formed of a second polyamide material surrounding the core along its length, the second polyamide material having dispersed therein non-absorbable radiopaque nanoparticles comprising 15-25% by weight of the second polyamide material. The melting point of the first polyamide material is at least 30° C. greater than the melting point of the second polyamide material. The core may also include or be formed of previously extruded bundles of first polyamide filaments overcoated with a second polyamide sheath. The suture is made by coextruding the core and a molten organic material formed of the second polyamide material and dispersed radiopaque nanoparticles. Desirably, the first polyamide material is Polyamide 66 and the second polyamide material is Polyamide 6.
