This chapter deals with cramps and spasms of striated muscles, providing readers with a diagnostic track through a terrain with common and uncommon neurologic symptoms of which some are poorly understood and therefore vaguely defined. Cramp describes an unwilled, transient, maximal and thus usually painful contraction of a single muscle or even parts of it, typically with a visible or palpable knotting. Common cramps that afflict otherwise healthy people, usually involve a few muscles and occur in a few characteristic situations. The group of symptomatic cramps comprises neuromuscular, endocrine, metabolic and toxic causes of cramps. Although a prominent feature in the stiff-man syndrome and in tetanus, exaggerated startle is generally considered an uncommon neurologic sign. In other neurological diseases, exaggerated startle typically occurs in the company of brain stem lesions. In cases with frequent cramps without treatable cause, membrane stabilizing drugs may reduce both frequency and intensity of cramps.