It was sometimes difficult to differentiate between acute-onset chronic inflammatory demyelinating polyneuropathy (A-CIDP) and subacute inflammatory demyelinating polyneuropathy (SIDP). The CNS involvement of these polyneuropathies has rarely reported in the literature. We present the case of a 42-year-old man who developed rapidly developing inflammatory demyelinating polyneuropathy followed by right optic neuritis. This case showed progressive motor weakness and sensory dysfunction with time to nadir at 8 weeks, demyelination in nerve conduction study, no other etiology of neuropathy, no relapse during follow-up of 18 months, good response to steroid and complete recovery which favor SIDP more than A-CIDP. We experienced the case of SIDP associated with optic neuritis.