Sister Mary Anne O'Brien, RSM, entered eternal life on Wednesday, August 2, 2023. A native of Ireland, Sr. Mary Anne was the seventh of nine children of Mary Anne and Patrick O'Brien.

Upon completion of her high school education with the Presentation Sisters she entered the Sisters of Mercy at Webster Groves MO in September 1951.

Her first ministry assignment in 1956 was in Mississippi where her brother, Rev. John t. O'Brien was a priest. She remained in Mississippi until she retired at Catherine's residence in St. Louis in 2018. Sr. Mary Anne held degrees from Webster College, Marquette University and the University of Southern Mississippi. She served as an elementary and high school teacher and she also taught ECD on weekends and during the summers. She spent six years as administrator of McAuley Home, a retirement home for the Sisters of Mercy in Vicksburg. In addition, she served as a psychologist at Gulf Coast Mental Health Centers, Catholic Social Services Biloxi. Her final and longest ministry was at St. Thomas Parish in Long Beach where she served in various capacities, including being Chaplain to the St. Vincent de Paul Society. She also volunteered for a short time at the local jail. While at Gulf Coast Mental Health Center she introduced a program for bereaved  parents. She continued this ministry throughout the rest of her live.

Sister Mary Anne is survived by 1 sister, 14 nieces and nephews; 31 grand nieces and nephews and 1 great-great niece.

Visitation on Tuesday, August 8, at Catherine's Residence, in St. Louis, MO  will begin at 10 a.m. followed by Mass at 11 a.m. A graveside service will be held at 11 AM on Thursday, August 10 at Cedar Hill Cemetery in Vicksburg, MS.