Three Hearts Marathon (Slovene: Maraton treh src) is a marathon, organised in Radenci in Slovenia.

It has been taking place since 1981 and attracts several thousand people each year.

In addition to the marathon, a half marathon (21 km), recreative running (10 km) and a course for juniors and teenagers are organised.

The event was the Slovenian national championships race from 1992 to 1998 and has hosted the national race in even-numbered years since then, now sharing the honour with the Ljubljana Marathon.

[1] The 2020 edition of the race was postponed to 2021.05.15 due to the coronavirus pandemic, with registrants having the option of obtaining a refund.