OBJECTIVE: To obtain magnetic resonance imaging (MRI) and serum miR-155 expression from patients with cerebral small vessel disease (CSVD), and therefore investigate their changes and significance. STUDY DESIGN: The study subjects were 88 patients admitted to our hospital between October 2019 and December 2020. The patients were grouped by the recorded results of their cranial MRI, namely single group (lacunar infarction, n=36), multiple group (multiple lacunar infarction with a complication of white matter lesions, n=52), and control group (healthy volunteers, n=40). Subsequently, serum miR-155 expression in each group was detected by RT-qPCR. The expression of IL-6, IL-1β, TNF-α, and IFN-γ levels in serum were observed by ELISA. Additionally, Pearson correlation analysis was performed for serum miR-155 expression and lesions seen on MRI in CSVD patients. RESULTS: In comparison with the control group, upregulated miR-155 expression in both the single and multiple groups was found, but its expression was higher in the multiple group. In comparison with the control group, increased expression of serum IL-6, IL-1β, TNF-α, and IFN-γ in the other two groups was revealed, but their expression was higher in the multiple group. According to Pearson correlation analysis, in CSVD patients, serum miR-155 expression was of a positive relationship with the increase of lesions on MRI. This meant that highly expressed miR-155 was associated with increased lesions. CONCLUSION: miR-155 expression in patients with different degrees of CSVD is different, and the higher the level of miR-155, the more imaging lesions. © Science Printers and Publishers, Inc.