The paper presents ultrastructures observed for the first time by aedeagus and spermatheca SEM of a plant pest (Coleoptera: Chrysomelidae: Cryptocephalinae) Cryptocephalus turcicus Suffrian, 1847 from Turkey. In the present study, the morphologies of male and female genitalia of this species belonging to the nominative subgenus Cryptocephalus (s.str.) collected from Ankara, Kastamonu and Samsun provinces are examined using SEM (Transmission Electron Microscopy). To date, there has not been a study in Turkey in this context in which male genitalia (aedeagus) and female genitalia (spermatheca) morphologies of the Cryptocephalus turcicus Suffrian, 1847 have been studied together. The genus Cryptocephalus is represented by 73 species in Turkey. Detailed investigations of aedeagus and spermatheca are very important to obtain new diagnostic characters in the genus Cryptocephalus. For this reason, ultrastructural and detailed investigations of aedeagus and spermatheca of Cryptocephalus turcicus Suffrian, 1847 from Turkey were firstly studied with SEM and stereo microscope to obtain new diagnostic characters in the genus Cryptocephalus. The new diagnostic characters obtained by examining the ultrastructure of aedeagus and spermatheca belonging to the species will be used in the distinction of species that are especially similar to each other, by determining the differences and important characters among the species in the genus Cryptocephalus. Photos in SEM, as well as photos in the stereo microscope, are also given in the text.