The aim of this study is to determine the prevalence of subclinical mastitis and the causative microorganisms in ewes in Siirt province, where small ruminant farming is widespread. The study used 349 ewes between days 50 and 80 of lactation. Milk samples were taken from the ewes and subjected to the California Mastitis Test (CMT). Scoring was performed according to the gelling stage. Milk samples were collected from ewes into sterile plastic tubes for somatic cell count (SCC) and bacterial isolation. Somatic cell count measurements were performed using the cell counter device. Bacterial analyses were carried out in the microbiology laboratory. In total, 349 sheep were evaluated, of which 198 (56.73%) tested positive for CMT and 151 (43.27%) tested negative. Furthermore, while bacterial growth was not detected in 145 (41.55%) of the 349 ewes, it was detected in 204 (58.45%). Coagulase-negative Staphylococcus (n:119, 58.33%) was the most frequently detected, followed by Mycoplasma agalactiae (n:35, 17.16%). Following these bacteria, Escherichia coli (n:15, 7.35%), Klebsiella pneumoniae (n:10, 4.90%), Staphylococcus aureus (n:10, 4.90%), Enterococcus spp. (n:5, 2.45%), Non-enterobacteriaceae (n:5, 2.45%), Corynebacterium spp. (n:2, 0.98%), Micrococcus spp. (n:2, 0.98%), and Streptococcus spp. (n:1, 0.49%) were isolated. In conclusion, a high prevalence of subclinical mastitis was found in Siirt province. It was concluded that informing farmers about the implementation of mastitis prevention and control programs would be beneficial.