Events & Pricing1/2 Marathon 10K Run5K
Submitted up to December 31$45.00$30.00$20.00
January 1 - February 5$60.00$35.00$25.00
February 6 - March 6$80.00$45.00$35.00
March 7 - March 16$90.00$50.00$40.00
Last Gasp Registration
(Available at Pre-Race Packet Pick-Up and on Event Day)
Seniors (60+) up to December 31$50.00$25.00$15.00
Seniors - January 1 to February 5$55.00$30.00$20.00
Seniors - February 6 to March 5$75.00$40.00$30.00
Seniors - March 5 to March 16$85.00$45.00$35.00
Kids' Dash (10 and under)$10.00


Register Online- Online registration for the 45th Annual Mercer Island Half has closed.

Registration is still available on Saturday at the Mercer Island Community & Event Center from 11:00am-4:00pm and on Race Day starting at 6:30am.

Register by Mail

Prefer to print out and send in a printed registration form, with payment by check?

Download the registration form here.

Bloomsday Run 2nd Seeding Qualification Info:

The Mercer Island Half Marathon is once again a qualifying race for the Bloomsday Run and their 2nd Seeding program.

What is 2nd Seeding you ask? 2nd Seeding is a special starting area on Riverside Ave reserved for runners who either placed in the top five in their age group in the previous year’s Bloomsday or who have run a “qualifying event” (Like the Mercer Island 10K) in the appropriate qualifying time (Men – 39:00, Women – 47:00).

If you plan to use your 10K time to register for second seeding in Bloomsday, you must pre-register for Bloomsday. Once you have qualified, contact Bloomsday’s second seed coordinator (through the above link) to coordinate getting registered as a second seeded runner. To receive more information on how to qualify and what steps to take after qualifying, please visit the Bloomsday Run’s 2nd Seeding page here:

Bloomsday – Second Seeding Informational Page