The article presents the results of studies of liquid extracts from Plantago major, Hedera helix and Salvia officinalis obtained by percolation using Timatic Micro extractor of Italian manufacturer Tecnolab. During the experiment have been quantified active ingredients, namely polysaccharides by gravimetric analysis and flavonoids and hydroxycinnamic acids by absorption spectrophotometry. The results obtained have made it possible to determine the optimal conditions of medicinal plants extraction: raw material particle size, time of compression and decompression, in which the most extraction of active ingredients from plant material occurs. According to the quantification of the active ingredients it has been found that their highest yield is observed in the extraction of plant material of 0.5-1 mm fraction size and compression and decompression time of 4 and 2 min, respectively.