This paper observed a specific phenomenon with respect to the characteristics of ‘irrealis’-sentences in German texts. The ‘irrealis’-sentences mean the sentences which have a logical relationship between ‘condition and consequence’, although they do not contain a wenn-clause. Lots of German grammarians have studied this phenomenon, namely focused on the ‘condition-consequence’ sentence, but they have dealt with it just in isolated sentences and ignored the contextual conditions. That is the reason why they did not explain and describe its characteristic completely. Taken the awareness of such methodological problems as a starting point, this paper tried to explain the ‘irrealis’-sentences without a wenn-clause in view of the concerned contexts. The following factors of these sentences were treated: the conditions of their realization, the formal construction and the contextual structure.