Purpose: This study aimed to investigate the relation between sternocleidomastoideus (SCM) and abdominal muscles, to determine the relation between the ability of sitting actively and trunk muscles strength, to assess the role of muscle strength on functional status in Duchenne Muscular Dystrophy (DMD). Material and methods: Fifty nine DMD cases, whose functional levels were level 2 and level 3 according to the Vignos Functional Scale, (with mean age of 7.97±2.51 years) were included in this study. Muscles were assessed by means of manual muscle testing. Results: In the comparisons according to the functional levels, there was no significant difference between level 2 and levels 3 for SCM, rectus abdominus, oblique abdominal and erector spinal muscle strengths (p>0.05). There were significant differences of muscle strengths when erector spinal muscles were excluded between the children able to sit or unable to sit (p<0.05). When all the subjects were analyzed, a correlation was found between SCM and Rectus abdominus muscle strength (r=0.33, p<0.05). There was a significant correlation between SCM and Rectus abdominus muscle strengths in the children who were able to sit actively and who were in level two according to the functional scale (r=0.69, r=0.72, p<0.05). Conclusion: As a result, it is observed that SCM muscle strength is effective on trunk flexion in DMD. The SCM and abdominal muscle strength of children able to sit actively were higher than the children unable to sit. The contribution of these muscles to sitting was observed.