Background & Aims: The purpose of the present study was to investigate the effects of Stress Inoculation Training [SIT] on patients with dysfunctional attitudes and primary hypertension. Methods: The study sample included 60 subjects with primary hypertension (32 females & 28 males) referred to special clinics in Ahwaz. Those who had primary hypertension and dysfunctional attitudes based on Beck & Wiszeman Dysfunctional Attitudes Scale (DAS) were selected and after being matched for age, socio-economic status and lack of other diseases, they were randomly divided into experimental and control groups. Experimental group underwent an 8-session Stress Inoculation Training (SIT) program. Finally, all subjects of the two groups were assessed for dysfunctional attitudes and primary hypertension in posttest and three months fallow- up. Results: The results revealed a significant difference between the two groups in dysfunctional attitudes and primary hypertension at posttest and fallow- up. Moreover, experimental group in comparison to the control group showed significant improvement in dysfunctional attitudes and hypertension in posttest and three months follow up. Conclusion: Stress Inoculation Training (SIT) significantly decreased dysfunctional attitudes and primary hypertension; therefore, using SIT in hypertensive patients is recommended.