The habituation of the startle reflex in a paradigm using electrical stimulation was studied in 17 psychotic patients and 18 healthy controls. The magnitude of the R2 component of the blink reflex differed between the groups (ANOVA, F = 5.81; P = 0.022) and during the course of trials (F = 25.72; P < 0.0001). Furthermore a statistically significant interaction of diagnosis x trials (F = 3.34; P = 0.022) emerged suggesting that an impairment in habituation of startle is present in patients but not in healthy controls despite a comparable reactivity.