Tibial nerve entrapment at the tendinous arch of the soleus has not been reported. A 58-year-old woman suffered from pain in the sole of her left foot, which was aggravated by active plantar flexion or passive extension of the ankle. Computed tomography and magnetic resonance imaging revealed a hypertrophic lesion in the left popliteus muscle. The tibial nerve was pushed posteriorly by the lesion and compressed by the arch of the soleus. The arch of the soleus was divided surgically. Pain was resolved immediately after the surgery, and significant neurologic recovery was observed 1 year after the surgical treatment. This condition must be recognized as a different clinical entity than either lumbar radiculopathy or tarsal tunnel syndrome.