Introduction:
The early maladaptive schemas (EMSs), behavioral inhibition system (BIS), and behavioral approach system (BAS) can play a role in using defense styles, especially in drug abuse which may be a maladaptive defense style.

Aim:
The aim of this study was to examine the relationship between EMS and BIS/BAS with defense styles in the Iranian abusers of natural drug.

Material and methods:
In a cross-sectional design, we examined 316 abusers of natural drug (including abusers of opium and opium sap, henbane and marijuana) admitted at Niyayesh addiction treatment clinic in the city of Shiraz, Iran (male – 61.4%, female – 38.6%).

Results and discussion:
Correlational analyses revealed that EMSs were correlated positively with both neurotic and immature defense styles, and negatively with mature defense style. Also, BIS and all BAS subscales were related to both neurotic and immature defense styles, and each of BAS subscales was negatively associated with mature defense style. Finally, there were significant sex differences in EMSs, BIS, BAS subscales, and defense styles.

Conclusions:
We concluded that the EMSs, excess BIS and BAS subscales are important variables in using maladaptive defense styles and subsequently in tending toward natural drug abuse in the abusers of natural drug.