Abstract: Objective To investigate the expression profile of miR-122-5p in melanoma tissues and the effect of miR-122-5p on the proliferation, cell cycle and apoptosis of human melanoma cell lines SK-MEL-110 and A375. Methods The expression profiles of miR-122-5p in melanoma and pigmented nevus tissues were detected using real-time fluorescence quantitative PCR (qRT-PCR). SK-MEL-110 and A375 cells transfected with miR-122-5p inhibitor or negative control inhibitor (NC) I were examined for miR-122- 5p expression using qRT-PCR and changes in cell proliferation, cell cycle and apoptosis using MTT assay or flow cytometry. NOP14 mRNA and protein expressions in the cells were detected using qRT- PCR and Western blotting, respectively. Luciferase reporter assay was used to confirm the identity of NOP14 as the direct target of miR-122-5p. Results The relative expression of miR-122-5p in human pigmented nevus tissues and melanoma tissues was 1.23±0.270 and 7.65 ± 1.37, respectively. The relative expression of miR-122-5p in SK-MEL-110 and A375 cells transfected with miR-122-5p inhibitor was 0.21 ± 0.08 and 0.17 ± 0.05, respectively. miR-122-5p inhibitor obviously inhibited the cell proliferation and increased the percentage of cells in G1 stage in both SK-MEL-110 and A-375 cells, but did not cause obvious changes in the apoptosis of the two cells. miR-122-5p inhibitor did not significantly affect the expression level of NOP14 mRNA, but obviously increased the expression level of NOP14 protein. Luciferase reporter assay revealed a significantly lower luciferase activity in cells co-transfected with miR-122-5p mimics and wild-type psi-CHECK2-3’UTR plasmid than in the cells cotransfected with NC and wild-type psi-CHECK2-3’UTR plasmid (0.21 ± 0.14 vs 0.56 ± 0.1, P<0.01). Conclusion miR-122-5p expression is upregulated in melanoma tissues, indicating its involvement in the development of melanoma. miR-122-5p inhibits the proliferation of SK-MEL-110 and A-375 cells possibly by affecting the cycle through NOP14.