Osteosarcoma is the most common primary malignant tumour of bone occurring in children and young adolescents, and is characterised by complex genetic and epigenetic changes. The miRNA miR-486-5p has been shown to be downregulated in osteosarcoma and in cancer in general. To investigate if the miR-486 locus is epigenetically regulated, we integrated DNA methylation and miR-486-5p expression data using cohorts of osteosarcoma cell lines and patient samples. An upstream CpG island of mir-486 was shown to be highly methylated in osteosarcoma cell lines as determined by methylation-specific PCR and direct bisulfite sequencing. High methylation levels were seen for osteosarcoma patient samples, cell xenografts and cell lines based on quantitative methylation-specific PCR. 5-Aza-2’-deoxycytidine treatment of osteosarcoma cell lines caused induction of miR-486-5p in osteosarcoma cell lines. When overexpressed, miR-486-5p affected cell morphology. miR-486-5p represents a highly cancer relevant, epigenetically regulated miRNA in osteosarcoma.