This study describes a rare case of bilateral reversed palmaris longus muscle. An unusual variation was observed during the male cadaver dissection (60-year-old White). According to the literature, a reversed palmaris longus muscle may cause a compartment syndrome in the wrist area, carpal tunnel, and Guyon’s syndrome. Moreover, this particular variation of the reversed palmaris longus muscle is rarely reported and has the potential to cause compression of both the median and ulnar nerves. Thus, the described variation is also useful to the hand surgeon, as the anomalous muscle is an anatomical landmark for operations at this area. Morphological variability and clinical significance are reviewed.