Plants in general and especially protected ground plants have a beneficial effect on human health, performing a number of functions. One of them is microclimate improvement as a result of the increase in air humidity, air ionization, increase in the amount of oxygen and decrease in the amount of CO2 in air, as well as the reduction to some extent of noise pollution, which positively influences the human psyche.  Another important function of indoor plants is to clear the air of dust, toxic chemicals and pathogenic microorganisms that can cause various diseases. Plants produce biologically active volatile substances – phytoncides, which have antimicrobial properties.        Greenhouse plant collections were used as material for research. Phytoncide activity was determined according to the methodology of A. M. Grodzinski (1973). As a result of testing a large number of species, about 300, over several years, in order to determine their phytoncide content and using data from literature on growing indoor plants for decorative purposes and for improving air quality in medical institutions, we suggest an assortment of tropical, subtropical and succulent plants. Species with high phytoncide activity: Aglaonema commutatum Schott., Alocasia macrorhiza Schott, Aloe variegata L., A.arborescens Mill.,Anthurium andreanum Lindl., A.magnificum Lindl.,Aspidistra elatior Bl., Aucuba japonica Thunb. var.variegata, Begonia masoniana Irmsch., B. hereacleifolia Cham.et Schl.,B.manicata Brogn.,  B.maculata Radii, B. metallica W.G.Smith, Euonimus japonicus Thunb., Jasminum sambac (L.) Ait., J.polyanthum L., Kalanchoe blossfeldiana  V.Poelln., K.daigremontana Hamet et Perriet, K.pinnatums Kurz.,K.marmorata Baker, K.tomentosa Baker, Coleus hybridus Voss, Laurus nobilis L., Monstera deliciosa Lieb., M.karwinskii Scott., Nephrolepis exaltata (L.)Schott, N.corfifolia(L.)C.Presl,  Pelargonium grandiflorum Willd., P.odoratissimum Ait., P. Peltatum Ait., P.zonale Ait.,Peperomia clusiefolia Hook.,P.maculosa Hook, P. obtusifolia Dietr.,Hedera helix L., Rosmarinus officinalis L., Sanseviera grandis Hook, S.trifasciata Prain, Ficus benjamina L., F. elastica Roxb.ex Horn, Cisus antarctica Vent., Roicissus rhomboidea Planch., Dracaena draco L., D. deremensis Engl., D. marginata  Lam.,Tetrastigma voinierianum Pierre ex Gagnep, Philodendron selloum C.Koch., Ph.erubescens C.Koch et Augustin, Ph.scandens C.Koch et Sello, Syngonium podophyllum Schott, Xanthosoma  violaceum Scott.,Myrtus communis L., Plectranthus fruticosus L, Herit., P.coleoides var. Variegatus., Diefenbachia maculata G.Don, Acalipha wilkesiana Muell., Euphorbia tirucalli L., E. milli Moulin,Murraya paniculata Jasq., Justicia carnea Lindl, Ruellia amoena    Ness, Sanchesis nobilis Hook.f., Hibiscus rosa-sinensis L., Agave americana L., Yucca elephantipes Regel, Sanchezia nobilis Hook., Clivia miniata Regel , Haemanthus albiflos Jasq., Scheflera actinophylla Harms, Gasteria fasciata Haw., Hawortia obtusa Haw., Asparagus sprengeri Regel, A.falcatus Linn., Crassula arborescens Willd., Ophiopogon jaburan Lodd., Psidium cattleianum Sabine, Pittosporum tobira Dryand., Abelia x grandiflora Rehd.. The optimization of the indoor environment in medical institutions requires knowledge of the conditions and peculiarities of each room, so, actually, developing an ecological passport. It is also necessary to know the requirements and possibilities of each species used for this purpose.