Eight persons suffering from hysterical fits were treated by behavior therapy. In the first phase fits were produced by administering a mild electric shock. In later stages of this phase the patients were conditioned to the termination of the mild shock; they then had regular fits at shorter intervals. In the second phase social contingencies were withdrawn to test whether this would produce extinction of the fits. In the third phase the intensity of the electric current was increased so as to make it painful. The "punishment" trials were continued until the patients did not get a fit on three consecutive trials. At a six-month follow-up six of the patients had been completely free of fits, compared to a maximum previous fit-free interval of three months in most of the patients.