Patients with frontotemporal dementia (FTD) with no known diagnosis of ALS or family history of ALS were clinically and electrophysiologically assessed for the presence of ALS. Of 36 patients studied, five met criteria for a definite diagnosis of ALS and two had EMG findings suggestive of denervation in one limb. An additional five patients had prominent fasciculations and six other patients had trouble swallowing but all had normal results on EMG studies. One of the patients with fasciculations and a normal EMG study progressed to definite ALS over the course of 1 year.