Brothers of women with polycystic ovary syndrome (PCOS) were found to be at increased risk for cardiometabolic disorders. This risk may be exacerbated by concurrent poorly controlled hypertension. Angiotensin II receptor blockers are the most frequently used antihypertensive drugs. The aim of the present study was to compare blood pressure-lowering and pleiotropic effects of telmisartan between male siblings of PCOS probands and unrelated men. The study included 2 age-, blood pressure-, and mass index-matched groups of men with grade 1 hypertension: 24 brothers of women with PCOS (group A) and 26 brothers of healthy women (group B). All subjects were treated with telmisartan (80 mg daily). Blood pressure, glucose homeostasis markers, and plasma lipids, as well as plasma levels of total testosterone, bioavailable testosterone, androstenedione, uric acid, high-sensitivity C-reactive protein (hsCRP), homocysteine, fibrinogen, and 25-hydroxyvitamin D were measured before and after 12 weeks of therapy. At entry, there were between-group differences in the degree of insulin resistance, plasma levels of high-density lipoprotein-cholesterol, triglycerides, calculated bioavailable testosterone, androstenedione, hsCRP, and 25-hydroxyvitamin D. Although telmisartan reduced blood pressure in both study groups, this effect was stronger in group B. Irrespective of the study group, the drug improved insulin sensitivity and reduced circulating levels of uric acid and homocysteine, but these effects were more pronounced in group B than group A. Only in group B, telmisartan decreased hsCRP and fibrinogen, as well as increased 25-hydroxyvitamin D. The obtained results suggest that hypertensive male relatives of PCOS probands may gain less benefit from telmisartan treatment than unrelated hypertensive men.