The ministry of a deaconess is, in modern times, a non-ordained ministry for women in some Protestant churches to provide pastoral care, especially for other women. The term is also applied to some women deacons in the early church. The word comes from a Greek word, diakonos (διάκονος), for "deacon", which means a servant or helper and occurs frequently in the Christian New Testament of the Bible. Deaconesses trace their roots from the time of Jesus Christ through to the 13th century in the West. They existed from the early through the middle Byzantine periods in Constantinople and Jerusalem; the office may also have existed in Western European churches. There is evidence to support the idea that the diaconate including women in the Byzantine Church of the early and middle Byzantine periods was recognized as one of the major orders of clergy.
A modern resurgence of the office began among Protestants in Germany in the 1840s and spread through Scandinavia, the Netherlands, Britain and the United States. Lutherans were especially active. The modern movement reached a peak about 1910, then slowly declined as secularization undercut religiosity in Europe and the professionalization of nursing and social work offered better career opportunities for young women. A small movement still exists and its legacy is seen in numerous hospitals.
Non-clerical deaconesses should not be confused with women ordained deacons such as in the Anglican churches and the Protestant Church in the Netherlands.
The oldest reference to women as deacons occurs in Paul’s letters (c. AD 55–58). Their ministry is mentioned by early Christian writers such as Clement of Alexandria. and Origen. Secular evidence from the early 2nd century confirms this. In a letter Pliny the Younger attests to the role of the women deacons. Pliny refers to "two maid-servants" as deacons whom he tortures to find out more about the Christians. This establishes the existence of the office of the deaconesses in parts of the eastern Roman Empire from the earliest times. Fourth-century Fathers of the Church, such as Epiphanius of Salamis,Basil of Caesarea,John Chrysostom and Gregory of Nyssa accept the ministry of women ordained deacons as a fact.