BACKGROUND: We investigated the effect of short-term telmisartan usage in addition to lifestyle changes such as diet and exercise on insulin resistance, lipid metabolism, and serum adiponectin and tumor necrosis factor-alpha (TNF-α) levels in hypertensive patients with metabolic syndrome (MetS). METHODS: A total of 36 hypertensive patients with MetS were randomized to telmisartan and control groups in an open-labeled prospective study. RESULTS: There were significant decreases in anthropometric variables of patients according to baseline measurements in both groups at the end of the study. Serum insulin level and insulin resistance assessed by homeostasis model assessment-insulin resistance were decreased significantly in the telmisartan group (P = 0.040 and P = 0.034, respectively) compared with the controls, while there was no statistically significant change in the lipid profiles of the two groups. Serum adiponectin level was increased by 19.1% ± 41.7% in the telmisartan group, but intergroup analysis revealed no significant change. There was also no significant change in serum TNF-α level in either group. CONCLUSION: It has been observed that even short-term telmisartan treatment had favorable effects on insulin resistance and glucose metabolism compared with lifestyle changes alone. The fundamental effect of telmisartan treatment on insulin resistance renders it a good therapeutic option for hypertensive patients with MetS.