Muscle degeneration in Duchenne muscular dystrophy (DMD) is exacerbated by the endogenous inflammatory response and increased oxidative stress. A key role is played by nuclear factor (NF)-κB. We previously showed that flavocoxid, a flavonoid with antioxidant and anti-inflammatory properties, ameliorates muscle pathology and function in mdx mice. This effect seemed to be mediated by the inhibition of NF-κB, tumor necrosis factor-α, cyclooxygenase-2/5-lipoxygenase and MAPKs expression in muscle. Moreover, flavocoxid has been shown to decrement serum levels of IL-1β and TNF-α in in vivo studies. Primary end-point of this pilot study was to evaluate safety and tolerability of flavocoxid administered daily per os for one year in ambulant DMD patients. We also evaluated function, muscle strength and quality of life. The effects of flavocoxid on selected biomarkers was also assessed. We enrolled 20 patients. We did not report any treatment-related adverse event and clinically meaningful change in laboratory findings. Serum expression analysis of inflammatory cytokines showed a significant reduction of TNF-α and IL-1β and oxidative stress markers (p<0.05). The results of the multidimensional clinical evaluation showed an overall stabilization of clinical course, even in patients older than 7years who showed a deterioration in the year before baseline. Moreover, a significant worsening of North Star Ambulatory Assessment was shown at 6months after end of treatment compared to all trial time points (p<0.05). We demonstrated that flavocoxid at this dosage is safe, also in pediatric age and in association with corticosteroids, and able to exert its biological effects on inflammatory pathways relevant to DMD pathogenesis.