Grindstone 100 Miler is an annual 100 mile long ultramarathon that takes place on trails in Virginia's Allegheny Mountains, usually held during the end of September.

Beginning at Camp Shenandoah, this out-n-back course ascends and descends Little North Mountain before climbing over 2,400 ft (730 m) in 4 miles (6.4 km) to the summit of Elliott Knob.

Runners continue north to Briery Branch Gap before retracing their steps (without summiting Elliott & Reddish) back along the course to Camp Shenandoah.

First place overall male and female runners will receive the Grindstone Champion's trophy.

The race is a triple qualifier for UTMB Mont-Blanc, Western States Endurance Run and the Hardrock Hundred Mile Endurance Run.