Microalbuminuria, and recently, hypoadiponectinemia, have been associated with progression of atherosclerotic disease and increased cardiovascular risk. We examined the possible associations of urinary albumin excretion, expressed as the ratio of albumin to creatinine (ACR), with plasma adiponectin and high-sensitivity C-reactive protein (hs-CRP) levels in men who had essential hypertension. The study population consisted of 108 men who did not have diabetes and were newly diagnosed with stage I to II essential hypertension (age 44.6 years, office blood pressure 148/95 mm Hg) and 110 men matched according to age and body mass index as controls. According to ACR values, which were determined as the average of 2 nonconsecutive overnight spot urine samples, subjects who had hypertension were categorized into 2 groups: those who had microalbuminuria (n = 28; mean ACR 30 to 300 mg/g) and those who had normal albuminuria (n = 80; mean ACR <30 mg/g). Subjects who had hypertension compared with controls exhibited higher ACR and log hs-CRP levels and a trend toward lower log adiponectin values (p = 0.062), whereas those who had normal albuminuria compared with controls had similar log adiponectin levels but significantly higher levels of ACR and log hs-CRP. Moreover, subjects who had hypertension and microalbuminuria compared with those who had hypertension and normal albuminuria had higher log hs-CRP and lower log adiponectin concentrations independently of confounding factors. Among those who had hypertension, ACR exhibited an independent positive correlation with log hs-CRP and a negative correlation with log adiponectin. Multiple linear regression analysis showed that age, body mass index, systolic blood pressure, log hs-CRP, and log adiponectin were significant independent predictors of the ACR. In conclusion, microalbuminuria is accompanied by decreased adiponectin and increased hs-CRP levels in the setting of essential hypertension, reflecting a rather diffuse atherosclerotic process.