We examined the coordination between right and left hindlimbs during voluntary forward swimming in adult red-eared turtles, before and after mid-sagittal section of the spinal cord hindlimb enlargement (segments D8-S2) or the enlargement plus the first pre-enlargement segment (D7-S2). Our purpose was to assess the role of crossed commissural axons in these segments for right-left hindlimb alternation during voluntary locomotion. Mid-sagittal splitting severed commissural fibers and separated the right and left halves of the posterior spinal cord. Adult turtles (n = 9) were held by a band-clamp around the shell in a water-filled tank while digital video of forward swimming was recorded from below and computer-analyzed with motion analysis software. In a subset of these animals (n = 5), we also recorded electromyograms (EMGs) from hip extensor and/or hip flexor muscles on both sides. Surprisingly, splitting spinal segments D8-S2 or D7-S2 did not affect the strength of out-of-phase coordination between right and left hindlimbs, though hindlimb movement amplitudes were reduced compared to pre-surgical controls. These results show that commissural axons in the hindlimb enlargement and pre-enlargement cord are not necessary for right-left hindlimb alternation during voluntary swimming. We suggest that alternating propriospinal drive from the right and left sides of the forelimb enlargement maintains the out-of-phase coordination of right and left hindlimbs in the bisected-cord preparation. Our data support the hypothesis that descending propriospinal (forelimb-hindlimb) and crossed commissural (hindlimb-hindlimb) spinal cord pathways function together as redundant mechanisms to sustain right-left hindlimb alternation during turtle locomotion.