General characteristic and specific properties of polydimethyl- siloxanes (PDMS) have been presented. The fields of man's contact with PDMS (pharmacy, medicine, foodstuff, cosmetics) were discussed in details. Toxicological problems concerning PDMS application have been specially taken into consideration. The necessity of developing of the techniques of PDMS identification as well as its determination in pharmaceuticals, food and biological was stressed. The examples of using IR, FT- IR, ATR FT-IR, ASA, NMR, GC/AED and GC/MS methods to these purposes were given.