Clinical diagnosis of amyotrophic lateral sclerosis (ALS) in patients presenting with cramps and fasciculations may not be evident at the first consultation. Sequential reviews, clinical and neurophysiological, form an important part of clinical practice in such cases. Recent attempts to delineate a more benign group with cramps and fasciculations have lacked information on the long term profile, both clinical and neurophysiological. Four patients who were initially diagnosed as suffering from benign cramps and fasciculations, but who subsequently progressed to ALS, are described. We propose that a diagnosis of benign cramps and fasciculations should not be considered secure without a minimum follow up of 4-5 years.