Introduction: Calendula officinalis L. is aromatic herbaceous yearling of the family of Asteraceae. Ethanol extract, decoction and ointment of the plant is used to treat or relieve injury, trauma, erosion, purulent trauma or slow healing abrasions, furuncle, carbuncle, congelation,burn, bed sore, herpes and lichen as cream and spray. These pharmacological functions are related to carotinoid, stearin acid, triterpinoid, phenolic compound, polysaccharide, β-carotene, tannin, flavonoids found in flower of calendula officinalis [2, 3].Goal: To define biologically active substances in cultivated Calendula officinalisMaterials and Methods: Calendula officinalis has been harvested from Monos pharmacological institute, garden of medical plants and prepared according to the appropriate standards. β –carotene and flavonoids were quantified by spectrophotometer, Alkaloid, tannin and ascorbic acids were quantified by tetrameter, Extractive substances, ash and humidity were quantified by weight analysis[1]Results: Quantitative analysis of the flower of calendula officinalis has been carried out following first Mongolian national pharmacopeia and Russian National pharmacopeia XI and defined that β –carotene 1.4313%, alkaloids 0.1229%, flavonoids 2.8817%, tannin 1.2376%, ascorbic acid 0.0702%, extractive substances 40.18%, ash content 11.75% and humidity 5.95%. Flower of calendula officinalis has been extracted by water, 30%, 50% and 80% ethanol, then made comparative analysis on content of β–carotiene. When extracted by 80% ethanol, content of β – carotene was the highest or 150 mg. Therefore optimum extraction solvent quantity has been defined to be 80% ethanol.Microbiological analysis has not revealed anyorganisms and bacteria in solid extract of the plant.Conclusions:1) Quality and countable analysis of biological active substance in the flower of calendula officinalis has been completed.2) β –carotene the main active substance in cultivated calendula officinalis, is found to be 1.4 gr which that meets Mongolian National Standards of medicine.3) The 80% ethanol extract of calendula officinalis contained 150mg β –carotene, the maximum content of β –carotene. Hence optimum extraction solvent was found to be 80%ethanol and it will be and used for future research.4) Microbiological parameters of 80% solid extract of the plant has met quality requirements.References:1. государственная Фармакопея XI вûпуск 2. москва 1990. с.1462. Коновалова о.в. рûбалко К.с. БиологическиАêтивные веùества Calendula officinalis L.“растительнûе ресурсû”. 1990. т. 26. вûп.3.с.448-4633. Cetkovic G.S. Djilas S.M. Canadanovic-Brunet J.M. Tumbas V.T. Antioxidant properties of marigold extract. “Food research International”. 2004. V.37. p643-650