Objective: To investigate the effects of lower limb flexibility on the functional performance of children with Duchenne muscular dystrophy. Methods: Thirty children, whose functional levels were at 1 or 2 according to the Brooke Lower Extremity Functional Classification Scale, were included in this study. The flexibilities of the hamstrings, hip flexors, tensor fascia latae, and gastrocnemius muscles were evaluated in the children's dominant lower limbs. The children's functional performance was assessed using 6-minute walk tests and timed performance tests. The correlations between the flexibilities of the lower limb muscles and the performance tests were examined. Results: The flexibilities of the lower extremity muscles were found to be correlated to the 6-minute walk tests and the timed performance tests. The flexibility of the hamstrings (r = -.825), the gastrocnemius muscles (r = .545), the hip flexors (r = .481), and the tensor fascia latae (r = .445) were found to be correlated with functional performance as measured by the 6-minute walk tests (P < .05). Discussion: The results of the current study indicate that the flexibility of the lower limbs has an effect on functional performance in the early stages of Duchenne muscular dystrophy. More research is needed to determine the functional effects of flexibility on performance by adding long-term flexibility exercises to the physiotherapy programs of children with Duchenne muscular dystrophy.