Donacia kraatzi Weise, 1881 is a very poorly known aquatic leaf beetle. It was briefly described on the basis of only two female specimens from Amasya (Turkey). For more than a century, male of D. kraatzi has remained unknown and literature about the species was very poor. Taxonomic status of this species was a little complicated and synonymy was suspected (quote) with D. fastuosa Khnzorian 1962 which was described from Armenia. The present paper introduces a detailed description of the previously unknown male of D. kraatzi and remarks on the female. Also, photographs of habitus and genital structures of both sexes are given. Furthermore, taxonomic controversy of D. kraatzi and suspicious synonymy with D. fastuosa is discussed on the basis of new data provided here. Actual and possible geographical distribution of the species is also debated.