Plants subjected to stress display various defense mechanisms. On base of these mechanisms, stress-protective measures can be developed. This paper deals with protection brought about by putrescine. An in vitro system to impose drought stress was developed and the protective effect of putrescine on drought stress was studied. Putrescine brought about protection: Arabidopsis seedlings treated 2 days before the stress with 30 mM putrescine survived drought stress to ca. 90% whereas the nontreated control survived to only 10%. When tissue-cultured plants are transferred to ex vitro conditions they suffer from drought stress. A pretreatment with putrescine was beneficial for the transfer to ex vitro conditions in rose and lily.