The aim of this study was to describe misleading lower limb mono radiculopathy revealing peripheral nerve vasculitis. Retrospective review of eight patients with biopsy confirmed vasculitis presenting as mono-radicululopathy in a tertiary referral centre dedicated to patients with rare peripheral neuropathies. Patients presented with chronic (6/8) or acute (n = 2) radiculopathy in L4, L5 or S1 territories associated with subtle systemic signs. A diagnostic workup was performed because of secondary motor deficit, the absence of clear radicular compression or failure of initial treatment focused on pain relief. In all, nerve conduction studies showed signs of asymmetrical axonal peripheral neuropathy (mononeuritis multiplex). Necrotizing vasculitis was eventually confirmed by peripheral nerve biopsy. Biological markers of inflammation or eosinophilia were present in 5/8 and a progressive motor deficit (7/8) is suggestive of the diagnosis. Under steroid treatment, all patients improved during a mean of 2 years 6 months of follow-up (Mean Rankin score improvement 1.9 point), but five relapsed including three mononeuritis multiplex, and one had acral necrosis. Vasculitis presenting as LL radiculopathy is rare; EMG studies with signs of mononeuritis multiplex and nerve biopsy studies are useful for making the diagnosis.