The cucumber plant (Cucumis sativus L) is an important cultivated plant produced worldwide. Cucumber mosaic virus (Cucumber mosaic virus, CMV), one of the common viral diseases, causes economic losses by reducing the yield and quality of the cucumber plant. In the observations performed in Diyarbakır in September 2021, cucumber plants showing virus-like symptoms such as mosaic, irregular yellowish spots, and deformity on the leaves were observed. Symptomatic and non-symptomatic samples were collected and subjected to a polymerase chain reaction (PCR) using CMV-specific primers, and the produced DNA bands were visualized on an agarose gel. CMV infection was detected in seven of the 15 samples. Bacterial cloning and sequencing of a randomly selected specimen determined that the CMV partial coat protein gene was 593 bp long and was registered in the NCBI database with the accession number MW962979.1. According to the phylogenetic tree performed with different isolates of CMV, Diyarbakir CMV isolate clustered with CMV isolates from Australia, Israel, Spain, Hungary, Japan, and Korea forming Subgroup IA. The presence of CMV and group/subgroup diagnosis in cucumber plants grown in the Diyarbakır region were confirmed molecularly for the first time by this study.