Event or Permit Cancellation: If for any reason the event is cancelled due to an act of nature or other Forest Service permit issues, the race director will make every effort to refund all unobligated funds to entrants or roll over entry fees to a rescheduled race date. Entrants need to understand and accept the fact that there are always risks involved in staging an ultra in the wilderness and there can be no guarantees that all entry fees will be refunded if the run is not held as advertised.

To Apply: Applications for entry to the 2021 race will again be accomplished using: UltraSignup beginning January 1, 2021. There will be a three day entry period and then a lottery (if required due to more than 300 qualified applicants) will ensue to select the entrant field. A waitlist signup will open immediately following the finalized results of the lottery or after the field has reached the 300 limit.

Click on the logo to sign up

Qualifications: Entrants must show proof of finishing an official sanctioned 50-mile race within the event time limits and within 13 hours from January 1, 2019 through January 30, 2021. The completion of a 100 mile or 100K event during the last 2 years will also serve as qualification.

As a requisite for participation, entrants are required to volunteer 6-hours towards trail maintenance or volunteer work at a running/community event. This requirement must be accomplished prior to June 1 with mail or email notification (to the RD) once the service is completed. We expect the greater San Diego area participants to complete their volunteer service on the San Diego trails we use for the 100 miler. Information about the San Diego Trailfit program and how to sign up for a workday are located at: San Diego Trailfit.

The Volunteer Service Requirement Certification Letter is located in the Essential Documents section on the SD 100 homepage. This form can be mailed or sent via email to

Entry Fee: Entry to SD 100 is $280 plus the Ultra Signup fee. If an entrant withdraws from the event and notifies the race director prior to March 1, 2020, they are entitled to a 50% refund and than $100 between March 1st and April 15th. No refunds after April 15th. No rollovers or transfer of entries permitted once an applicant is a confirmed entrant.