Drimnagh Castle Secondary School (Irish: Meánscoil Iognáid Rís) is a Christian Brothers secondary school located on the Long Mile Road in the suburb of Drimnagh, Dublin, Ireland.

For a short time after the school opened, classes took place in the castle itself, until the current buildings were completed at a cost of £84,000.

The school was not free of sexual abuse during the decades when it proliferated in Irish society.

As the years passed the numbers of brothers teaching in the school gradually fell, and there are currently[when?]

The occasion was celebrated by the addition of a new sports changing facility which was officially opened on 4 October 2004 by President Mary McAleese.