Herbs have been of great interest in recent years. Peppermint is one of the most popular species in Poland used in the form of herbal tea. The objective of the research was to determine and compare the content of essential oils obtained from peppermint in a loose state and after producing agglomerate therefrom. The scope of the research covered compression of grated peppermint and fractions separated from it. Fractions were separated with the use of a sieve with 2.5 mm square meshes and compressed with a hydraulic press with a closed matrix under the pressure of 193.86 MPa. Before and after the agglomeration process, density of the investigated material and the content of essential oils were determined according to the pharmaceutical requirements by a distillation method on Clevenger's apparatuses. The lowest content of essential oils was in case of the fraction of grated peppermint which did not go through the sieve with 2.5 square meshes. Compression of this material to the level o 1.038 g·cm-3 resulted in the reduction of oil content by approximately 9%. In case of the remaining fractions, no losses of oil as a result of compression were reported.