The Mass compositions of G. F. Anerio, chapelmaster at king Sigismund III’s court, constitute the part of his musical achievements most closely connected with the stylistics of Palestrina present in his renditions of the ordinarium missae. Amongst the Masses by Anerio one can find pieces using pre-compositional material and thus belonging to the missae ad imitationem type and the Mass with cantus firmus. A set of three missae breves is formally and structurally distinctive. His overall achievement in the area of Masses can be divided into monochoral and polychoral pieces. The essential elements of the music techniques of the composer of the Missa Constantia did not change during the whole period of his artistic activity. Predominant in his achievements was the ad imitationem type of Masses (they also included the Missa Constantia, based on an unknown model, composed to honour Sigismund III’s wife) where the method of the use of pre-composition material is in conformity with the practice of parodying, developed in the sixteenth century.