A case complicated with colorectal and prostate cancers in paraneoplastic(subacute)cerebellar degeneration(PCD)is extremely rare. We report a retrospective case of rectal carcinoma with paraneoplastic cerebellar degeneration. A 79-year-old man with Parkinson's disease was unable to walk because of paralysis. Brain MRI showed cerebellar atrophy. He was admitted to our hospital for anal bleeding and was diagnosed with colon cancer. An associated diagnosis of PCD was made. After resection, his paralysis and dysarthria were resolved to the extent of beingable to walk and speak fluently. Brain MP-RAGE showed no findings suggestive of metastasis or atrophy. He was treated surgically, which resulted in a transient improvement in PCD symptoms. Per blood testing, cytokines IL-6 and IL-10 were lower postoperatively. Immunosuppressive levels of myeloid- derived suppressor cells(MDSCs)were lower compared with the preoperative values. Thus, innate immunocompetence and resolution of paralysis followed the surgical intervention.