Hundreds of events are taking place right around the country for Shave or Dye 2015.
It's the sixth year of the campaign - and so far more than 7.5 million euro has been raised for the Irish Cancer Society.
As part of Shave or Dye, we're profiling some of the people affected by cancer, and those who help them.
Juliette Gash caught up with Robbie Lunn, who was diagnosed with Bowel cancer aged just 22;
You can get involved with Shave or Dye or Oh My! Here:http://www.todayfm.com/shaveordye2015