The aim of the current work was to investigate developmentally induced cytosolic small heat stress proteins class I and II (sHSP’s) to get information on the function of these proteins in plants. Nicotiana tabacum seeds served as model system. Northern and Western blot analysis and immunohistology were used to determine the presence of sHSP’s and their mRNAs in seeds at different stages of development and germination. The expression of sHSPs and globulins started simultaneously at about the 17th day after anthesis. During seed germination the disappearence of sHSPs paralleled with the storage protein disappearence. Furthermore, in embryos of transgenic tobacco plants , which do not contain any protein bodies and storage proteins, no sHSPs were found. Thus, the occurence of sHSP’s in plant duration organs seems to be associated with the presence of storage proteins. To prove this assumption we have investigated the state of other plant quiescent organs with respect to their sHSP’s content. We have found sHSP`s in one year old twigs of Acer and Sambucus and in the liana Aristolochia exclusively in winter months. In tendrils of Aristolochia sHSPs were localized in fasciular cambium cells. After budding, in spring time, these proteins were no longer present. Furthermore, accumulation of sHSPs was demonstrated in Narcissus bulbs and potatoes tubers. In potato tubers and bulb scales of Narcissus the stress proteins were localised in the central vacuoles of storage parenchyma cells. Our data indicate, that the expression of non heatstressed induced sHSPs seems to be essential for resting plant organs, accumulating large amounts of storage proteins.