Aim. The recent discovery of small non-coding RNAs, so-called micro RNAs (miRNAs), has provided new insights into cancer diagnosis. Several studies have shown that profiles of miRNA expression differ between normal tissue and tumour tissue and vary among tumour types. To exploit this difference, we evaluated the feasibility of using muscle-specific miRNAs (miR-1, 133a, 133b, 206) as biomarkers of rhabdomyosarcoma (RMS). Method. Total RNA was extracted from 16 cell lines (7 RMS, 4 neuroblastoma, 3 Ewing sarcoma and 2 malignant rhabdoid tumour) and 21 tumour specimens (7 RMS, 1 Ewing sarcoma, 4 undifferentiated sarcoma, 1 osteosarcoma, 1 alveolar soft part sarcoma, 2 neuroblastoma, 2 Wilms tumour, 1 malignant rhabdoid tumour, 1 adrenal carcinoma and 1 retinoblastoma). miRNA was quantified by real-time RT-PCR. The expression levels of miRNAs were calculated utilizing the delta-delta Ct method, normalised to the level of miR-16, and compared using the Mann-Whitney U test. Results. The expression levels of muscle-specific miRNAs in the RMS cell lines were significantly higher (p<0.01) than those in neuroblastoma, Ewing sarcoma and malignant rhabdoid tumour cell lines. miR-206 was most abundantly expressed and miR-1 was least abundantly expressed among muscle-specific miRNAs in RMS cell lines. The expression levels of musclespecific miRNAs in RMS tumour specimens were significantly higher (p<0.01) than those in other pediatric tumours. The difference in the expression levels between RMS and other tumours was largest in miR-206. Conclusion. The expression levels of muscle-specific miRNAs were significantly elevated in RMS cell lines and tumour specimens. Muscle-specific miRNAs, especially miR-206, can be potential biomarkers for RMS diagnosis