A brief review of the genus Nalassus Mulsant, 1854 of Turkey is given. The new genus Turkonalassus gen. nov. (type species Helops adimonius Allard, 1876) is described. Species of the newly described genus are superficially similar to representatives of the subgenus Pelorinus of Probaticus (subtribe Helopina), but belong to the subtribe Cylindrinotina and are close to the genus Nalassus from which they differ by the absence of temple grooves ventrally (lower aspect of eye without ventral groove). The following species are included in Turkonalassus: Turkonalassus adimonius (Allard, 1876) (from Probaticus), Turkonalassus pentheri (Reitter, 1905), comb. nov. (from Probaticus), Turkonalassus bozdagus Keskin et Nabozhenko, 2010, comb. nov. (from Nalassus), Turkonalassus pineus sp. nov., Turkonalassus quercanus sp. nov., Turkonalassus petrophilus sp. nov., Turkonalassus macedonicus sp. nov. The last species is described from Greece and Bulgaria, the other species are known from Turkey. A new synonymy is established: Nalassus Mulsant, 1854 = Helopocerodes Reitter, 1922, syn. nov.; Turkonalassus pentheri = Cylindronotus hoberlandtii Kaszab, 1959, syn. nov. Lectotype of Helops pentheri Reitter, 1905 is designated. A key to the species of the genus Turkonalassus and genus Nalassus from Turkey is given.