OBJECTIVES: Retinoblastoma (RB) is a highly malignant eye tumor with a low survival rate and a high metastatic rate. The current work was designed to investigate the potential roles of microRNA-144 (miR-144) in the diagnosis and prognosis of RB. METHODS: miR-144 expression levels in RB tissues and adjacent normal tissues, as well as serum samples from RB patients and healthy controls were measured. The association between miR-144 expression levels and clinical features were analyzed. Moreover, diagnostic and prognostic values of miR-144 in RB were verified by receiver operating characteristic analysis and Kaplan-Meier survival assays. RESULTS: The expression level of miR-144 was markedly decreased in tumor tissues of RB patients, and the expression level of miR-144 was positively associated with tumor size and metastasis in RB patients. Moreover, miR-144 can distinguish tumor tissues from normal tissues with high specificity and sensitivity, and RB patients with lower miR-144 expression have shorter overall and disease-free survival rates than those with higher miR-144 expression. Alternatively, miR-144 also decreased in the serum of RB patients in comparison with healthy subjects, and miR-144 expression levels in the tissue samples and serum were positively correlated. Furthermore, miR-144 levels in the serum of RB patients sensitively distinguished RB patients from healthy controls. CONCLUSIONS: miR-144 expression was downregulated in serum and tissue samples of RB patients and may function as a diagnostic and prognostic marker for RB.