Postoperative radiculopathy has previously been reported as a common complication of transforaminal lumbar interbody fusion (TLIF). However, no data has been published on lumbar plexopathy following TLIF. We present a rare case of lumbar plexopathy occurring following TLIF (L5-S1) in a patient with spondylolisthesis. Although initially a diagnostic challenge, sinister causes of neuropathy such as bleeding or neoplastic growths were excluded by imaging. A diagnosis of acute lumbar plexopathy of left L2 to L4 was eventually made after electromyographic studies was performed in consultation with a senior neurologist. The patient was treated supportively with good functional recovery.