The original language of the New Testament was Greek, and the Church has always used the Septuagint - a pre-Christian translation of the Hebrew Old Testament into Greek - because this is considered to be more accurate than the Hebrew Masoretic Text (dating from the 7-10th centuries AD) used by Jews and Protestants today.
However, except for those Orthodox parishes which use Greek as their primary liturgical language, Scripture readings will be from a translation into whatever language is used for the rest of the Liturgy - Slavonic, Romanian, English, etc.
In the West, most translations of the Old Testament are based on the Masoretic Texts rather than the Septuagint used by the Church. For that reason, many Orthodox churches currently use translations of the Bible that are not based on the Greek text. Hopefully this will change as better translations from the Septuagint become available in those languages.