The Bon Secours Health System is the largest private healthcare provider in Ireland with 2,500 staff.
It has technically advanced hospitals in Cork, Dublin, Galway and Tralee.
This week it bought Barringtons Hospital in Limerick for just under €15m.
The company made a profit of €2.3m for the year ending December 2015.
The company has its origins in the Bon Secours religious order which
originated in France and then expanded into Ireland in the 19th Century.
The company is led by a seven-member board of management which includes one Bon Secours sister.
However, three-quarters of the directors who served on its board
between 1994 and 2016 were members of the religious congregation.
And, according to Companies Office records, nuns acted as secretaries to the board for a little over half that time.
Of the total 25 directors listed for that period, 17 were listed as
Bon Secours sisters or - where the title was not stated - as living in
convents owned by the congregation.
They ranged in age from 48 to 76, and most were in their 60s at the time of their appointments.