Objective To explore the relationship between aggressive behavior with thyroid hormone or cortisol and in schizophrenic patients. Methods According to the past violence history and modified overt aggression scale( MOAS) weighted total scores,108 schizophrenic patients were divided into aggressive group ( n=69) and non-aggressive group( n=39) . Positive and Negative Syndrome Scale ( PANSS) total scores, serum thyroid hormone levels and cortisol concentration were compared between the two groups before and af-ter 2,4 weeks treatment. And correlations of PANSS and sub-scales scores,thyroid hormone levels and corti-sol concentration with MOAS weighted total scores and subscales scores were analyzed before these patients receiving treatment. Results Before treatment,total scores of PANSS,positive symptoms and general psy-chopathology scores in aggressive group((94.19±12.71),(23.77±4.94),(52.61±6.45))were higher than that in non-aggressive group ((83.26±11.21),(21.36±7.10),(45.49±6.84)) and these differences were significant(P<0.05). But the difference of PANSS total scores after 2,4 weeks treatment between the two groups was not significant (P>0. 05 ) . Free thyroxine ( FT4 ) level of aggressive group ( ( 14. 41 ± 3. 58 ) pmol/L) was higher than that of non-aggressive group ((12.95±2.66)pmol/L) before treatment and the difference was significant(P<0.05) . Meanwhile,there was no significant differences between the two groups in thyrotropic-stimulating hormone(TSH),free triiodothyronine(FT3),total triiodothyronine(TT3) and total thyroxine( TT4) levels( all P>0.05) . After 2 or 4 weeks treatment,the differences between the two groups in TSH,FT3,FT4,TT3,TT4 levels were not significant(P>0.05). The differences between the two groups of cortisol concentration were not significant before and after 2,4 weeks treatment(P>0.05) . MOAS weighted to-tal scores were positively correlated with PANSS total scores,negative symptoms scores,general psychopathol-ogy scores and level of FT4,and their r values were 0.471,0.204,0.531,0.239(all P<0.05). Verbal aggres-sion was positively correlated with PANSS total scores,positive symptoms scores and general psychopathology scores,and their r values were 0.213,0.215,0.292(P<0.05). Auto-aggression was positively correlated with PANSS total scores and general psychopathology scores,and their r values were 0.278,0.382(P<0.05) . Psy-chical aggression was positively correlated with PANSS total scores,negative symptoms scores,general psy-chopathology scores and level of FT4,and their r values were 0.361,0.193,0.338,0.276(P<0.05). Conclusion The total scores of PANSS,positive symptoms,general psychopathology scores,level of FT4 and their variances can reflect severity of aggression and predict aggressive behavior in schizophrenic patients. Concen-tration of cortisol is not associated with aggressive behavior and can not be used as a predictor of aggressive behavior in schizophrenic patients.