Background: Childbirth is an important experience in the woman's life; and its quality has short- and long-term effects on them. Objective: The present study aimed to determine the effect of positive mental imagery on the labor pain tolerance in primiparous women referred to Atieh teaching-medical center in Hamadan. Methods: The present clinical trial study (IRCT20120215009014N242) was conducted on 90 primiparous mothers referred to Atieh Hospital of Hamadan in interventional (n= 45) and control (n= 45) groups. Data collection tools included demographic information forms, Behavioral pain scale, Visual analogue scale (VAS), and the birth registration checklist that were responded by both groups through interviews and observation during labor. The intervention group participated in 4 weekly counseling sessions in groups of 5 to 7 participants, but the control group received only routine care. Finally, the obtained data from above questionnaires was analyzed using SPSS 21 and analysis of covariance (ANCOVA), Independent t-test and chi-square test and the significance level of tests was considered to be at the level of 5%. Results: The research results indicated that the mean age of control and intervention groups was 25.98±4.82 and 25.32± 4.85 respectively. The mean scores of Visual analogue scale (VAS) and the Behavioral Pain Scale significantly decreased compared to the control group (P <0.001). The mean scores of behavioral changes in the intervention group were 1.77 ± 0.68, 2.39± 0.54 and 3.09±0.60 in 4-5 cm, 6-7 cm and 8-10 cm dilatations respectively. That was statistically significant decrease compared to the control group (P=0.005). Conclusion: Positive mental imagery counseling reduced the visual analogue intensity and behavioral pain intensity in primiparous women. It seems that continuing education and counseling during pregnancy and empowering mothers to control themselves and learn mental imagery techniques and practice during pregnancy and childbirth can
