Two case reports of patients who developed a toxic neuropathy associated with nitrofurantoin are presented. In each case the patient had normal renal function and the symptoms abated upon withdrawal of the drug. Although the specific mechanism by which nitrofurantoin causes the neuropathy is still not known, various hypotheses are discussed and the literature is reviewed. The danger of nitrofurantoin administration in patients with impaired renal function is emphasized, and it is stress that early signs and symptoms of peripheral neuropathy be reported and the drug immediately discontinued. Even in the presence of normal renal function, the recommended dosage and duration of therapy should not be exceeded.