Primary lumbosacral plexus neuropathy (LSPN) is a well-defined syndrome characterized by pain, weakness and atrophy in the distribution of the lumbosacral plexus. Previous reports of LSPN have stressed the benign nature of the syndrome. Patients generally have a nearly complete recovery in months to years following the initial event. Two patients presenting with a relapsing form of LSPN are reported. The diagnosis of LSPN was based on clinical and electromyographic features, and no underlying cause was found on initial evaluation or subsequent follow-up over a 6- to 8-year period. We suggest that these patients represent a clinically and possibly pathologically distinct subgroup of LSPN.