Using the case records of Mayo Clinic patients, 121 patients with a diagnosis of benign fasciculations were identified. All had a normal neurological examination and normal electrophysiological studies, except for fasciculation potentials. Interviews by telephone were conducted 2 to 32 years after diagnosis. None of the patients developed symptomatic motor neuron disease. Forty individuals were in health care careers. A subset of 19 patients described acute onset of fasciculations following a viral infection. Benign fasciculations are not a prelude to progressive motor neuron disease.