In a previous paper,we have suggested that the second order complexity ApEn can be used as a measure of the degree of non-stationarity of a time series.In this paper,EEG data in deep coma and in brain-death state reeoded from the same patient were analyzed with this measure.The results show that the second order ApEn decreases significantly in brain-death state.It hints that the EEG signals in brain-death become less non-stationary,thus the second order ApEn might be an index for judging brain-death.