Introduction: Resistin is a peptide hormone, secreted by adipose tissue. Increased secretion of resistin results in insulin resistance and metabolic syndrome. The aim of this study was to determine the effect of hydro-alcoholic spinach (Spinacia oleraceae L.) extract on the expression of resistin mRNA in the visceral adipose tissue of rats exposed to chronic immobilization stress. Materials and Methods: In this experimental study, 30 adult male Wistar rats were allocated to six groups, including: 1) Control, 2) Spinach 200, 3) Spinach 400, 4) Stress, 5) Stress-Spinach 200 and 6) Stress-Spinach 400. Groups 2 and 5 were gavaged with spinach hydro-alcoholic extract at dose 200 mg/kg body weight and groups 3, 6 were gavaged with dose 400 mg/kg body weight of extract for 21 consecutive days; groups 4, 5 and 6 were placed in restrainers 6 hours a day for 21 consecutive days. At the end of this period, the expression of resistin mRNA in adipose tissue was evaluated by Real Time PCR. Data analysis was performed using one-way ANOVA and P<0.05 was considered significant. Results: Chronic immobility increased the expression of resistin mRNA (2.78±0.30) in adipose tissue, compared to the control group (1±0.36) (P=0.002). Resistin mRNA expression in visceral adipose tissue of Stress-Spinach 200 and Stress-Spinach 200 (0.74±0.23 and 1.45±0.15 respectively) was lower than in the stress group (P=0.000 and P=0.020 respectively). Conclusion: Results indicate that spinach extract can reduce resistin mRNA expression in rats exposed to chronic restraint stress.