Juvenile dermatomyositis (JDM) is the most common idiopathic inflammatory myopathy in children. Its outcome depends on the precocity of the diagnosis and of the treatment, but predictive parameters for guiding the correct therapeutic and prognostic approaches to JDM are still lacking. We analysed the one-year-old outcomes of 20 JDM patients treated with methylprednisolone boluses, methotrexate, and cyclophosphamide, through a longitudinal retrospective study. The outcome variables included: the Childhood Myositis Assessment Score (CMAS); Manual Muscle Testing (MMT); the Childhood Health Assessment Questionnaire (CHAQ); the Child Health Questionnaire (CHQ: physical score CHQ PhS and psycho-social score CHQ PsS), patient and parent Visual Analogue Scale (VAS), as well as laboratory data: ESR, LDH, CK, and ALT. Within all JDM patient groups, we discovered significant improvement in all disease activity parameters CMAS (p<0.001) and MMT (p<0.001), followed by a significant decrease in CHAQ (p<0.001), as well as parent VAS (p<0.001) and physician VAS (p<0.001). With regard to laboratory parameters, only CK (p=0.001) and LDH (p=0.013) levels were found to be significantly decreased, while there were no significant changes in ESR and ALT. The results of our study support the findings that the aggressive treatment of JDM patients improves their short-term outlook.