Hyssop (Hyssopus officinalis L.) comes from Mediterranean region. Cultural and wild forms grow in Europe, North America, and the Forest-Steppe and Steppe zones in the Eastern Europe. It is a perennial herbaceous semi-bush that ranges from 50 to 80 cm in height. In the study we performed experimental work on the basis of M.M. Gryshko National Botanical Garden of National Academy of Sciences of Ukraine (Kyiv city) and agrarian and biological station of Pavlo Tychyna Uman State Pedagogical University (Uman city, Cherkasy region). Allelopathic activity of water soluble (WSS), alcohol soluble (ASS) and volatile secretions (VS) was determined by biological tests (Hrodzynskyi, 1991) – one-day seedlings of garden cress (Lepidium sativum L.) in the model experiments. Comparative analysis of the activity of water soluble extracts of Hyssop showed that water soluble secretions from both above-ground organs and roots were characterized by high phytotoxicity recorded at the beginning of plant growth. Wheat coleoptiles were more tolerant to secreting; their activity was low in the condition of Kyiv city as well as Uman city. The authors have defined the following results regarding the reaction of winter wheat roots: secretions of all plant organs in the condition of Kyiv city were phytotoxic, but water soluble secretions from roots and stems had a stimulating effect and, on the contrary, secretions from leaves and inflorescences showed inhibitory impact in terms of Uman city. Most of plant ekzometabolites are accumulated in the soil of rhizosphere rhizoplan and contribute to its enrichment with organic compounds and mineral elements and also accumulation of humus. Received results showed dependence between accumulation of phytotoxic substances and soil type and climatic conditions. The conclusions are as follows. Different types of plant secretions of Hyssopus officinalis L. species during a vegetation period are analyzed. The largest number of substances with inhibitory action was localized in leaves and inflorescences. Blossoming phase was a demonstrative phase concerning allelopathic activity. Roots of garden cress were the most sensitive to secretions among selected test-objects. It was found that soil of rhizosphere and space between rows during a vegetation period accumulated colins, content of which depended on environmental factors and secretory functions of plants.