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After fumigation with experimentally generated low concentration of sulphur dioxide and sublethal freezing during the winter season the following changes could be noted with young spruces in autumn, shortly before, and in spring, at the end of the growing season: as a consequence of immission stress a depression of the net photosynthesis occurred without the stomata regulation capability being impaired. In spring the starch content of young shoots of the last year increased much less than that of the control plants. There was an increase of the electrolyte content within the diffusate from last-year shoots and the carbohydrate exsudation from roots as well. Freezing generally enhanced the permeation of substances from young shoots and roots, especially with plants exposed to SO2. It is supposed that the increased frost sensitivity of SO2— stressed plants is associated with a disturbance of controllability of the membrane permeability.