The aim of the current study was to assess the expression and clinical significance of serum microRNA (miR)-484 in patients with non-small cell lung cancer (NSCLC). Reverse transcription-quantitative polymerase chain reaction was performed to determine the expression of miR-484 in the serum of patients with NSCLC and NSCLC cell lines. Cell counting kit-8, flow cytometry, cell migration and cell invasion assays were performed to assess the role of miR-484 in the malignant changes associated with NSCLC cells. Furthermore, to assess the diagnostic value of miR-484, receiver operating curve (ROC) analysis was performed and the clinical relevance of serum miR-484 expression in patients with NSCLC was determined. A Kaplan-Meier analysis with the log-rank test was performed to assess the overall survival rate patients. To the best of our knowledge, the current study demonstrates for the first time that serum miR-484 was increased in patients with NSCLC compared with healthy controls. Additionally, serum miR-484 was revealed to be positively associated with histological grade, lymph node metastasis, distant metastasis and clinical stage. Patients with NSCLC and high serum miR-484 levels demonstrated significantly poorer overall survival rates compared with those exhibiting lower serum miR-484 expressions. ROC analysis revealed that serum miR-484 could screen patients with NSCLC patients from healthy controls with a high sensitivity and specificity. In vitro analysis also demonstrated that miR-484 was significantly upregulated in NSCLC cell lines, including 95D and H358 cells. Furthermore, the suppression of miR-484 decreased cell proliferation, cell migration and invasion. In summary, the results of the present study demonstrated that increased serum miR-484 expression is associated with the diagnosis and prognosis of patients with NSCLC. High serum miR-484 expression is associated with the diagnosis and prognosis of patients with non-small cell lung cancer