Spinal muscular atrophy (SMA) is a neurodegenerative disease characterized by spinal cord and brainstem motor neuron (MN) loss. Axonal transport defects are a common hallmark of MN degeneration and KIF5A, a major component of the axonal transport machinery, has been associated with MN diseases, but its role in SMA has not been elucidated yet. Our aim was to investigate a possible correlation between KIF5A and SMA pathogenesis. Therefore, Western Blot, qRT-PCR and immunohistochemistry analysis were performed to investigate KIF5A and its adaptor protein complex Miro1/Milton expression in the spinal cord of a mouse model of SMA, at different stages of the disease. Computational analysis was used to identify putative consensus sequences for microRNAs able to modulate KIF5A expression. Interestingly, our results showed a down-regulation of KIF5A and Miro1 in the spinal cord of SMA mice at P5 and P12, mirrored by an upregulation of mir-140-3p levels in this region. To assess the hypothesis that miR-140-3p could be a possible regulator of KIF5A expression, luciferase assay was performed and mice were intracerebroventricularly injected with antimiR140, a molecule able to specific block miRNA-140. Behavioral tests showed a slight increase in the lifespan of SMA pups and an improvement of their behavioral performance after antimiRNA administration. Therefore, our study suggests an implication of KIF5A in the anterograde transport defects observed in SMA mice and identifies miR-140-3p as a new possible therapeutic target for the treatment of the disease.