Introduction & Objective: Understanding the determinants of physical activity in patients with inflammatory bowel diseases is effective in controlling or reducing the complications of these diseases .The purpose of this study is to determine the effect of educational program based on transtheoretical model(TTM) on physical activity in patients with inflammatory bowel diseases.

Materials & Methods: This study is a semi experimental research .60 patients with inflammatory bowel diseases referring to Emam khomeini hospital in Ahvaz in 2008 were selected through purposeful method and then randomly divided into 2 groups.They completed questionnaires about demographics and physical activity before and after 1 month of intervention .The intervention program included tailored counseling and focus group based on transtheoretical model .d The data was analyzed with T-test and X2 using spss software.

Results: Our findings showed a significant difference for the effect of health educational program based on transtheoretical model on increasing change stages of self-efficacy ,decisional balance and physical activity behavior in the case group(P<0/05 )but showed no difference in the control group Also educational intervention caused significant difference between the 2 groups in self-efficacy ,decisional balance and physical activity behavior and finally the hypothesis of the study was confirmed.

Conclusion: Educational programs based on transtheoretical model have positive effects on observing the constituents of the TTM ,thus nurses can play an effective role in promoting the health level of the society through counseling and educating