['To evaluate the clinical factors predicting the significantly elevated high-sensitivity C-reactive protein (hs-CRP) concentrations, defined herein as hs-CRP > or = 3 mg/L, in adult males with untreated obstructive sleep apnea syndrome (OSAS).', 'Cross-sectional study.', 'Tertiary referral center.', 'Sixty-five consecutive male patients with newly diagnosed OSAS were enrolled to receive complete medical history review, physical examination, in-laboratory overnight polysomnography, and hs-CRP test. The patients had no current or history of cardiovascular disease. The patients had a mean age of 38.2 +/- 9.9 years, body mass index (BMI) of 27.4 +/- 3.5 kg/m(2), and Epworth Sleepiness Scale (ESS) of 11.3 +/- 4.6. The serum levels of hs-CRP were assessed using peripheral venous blood samples.', 'Twenty-three percent of the overall patients had significantly elevated serum levels of hs-CRP. The increase of hs-CRP correlated fairly with BMI, apnea-hypopnea index (AHI), tonsil size, and ESS (r = 0.450, 0.398, 0.393, and 0.300, respectively; all P < or = 0.05) after adjustment for conventional coronary heart disease risk factors. However, only the AHI could predict for significantly elevated hs-CRP after stepwise multiple linear regression (R(2) = 0.251, P < 0.001).'] Do patients with severe obstructive sleep apnea syndrome and elevated high-sensitivity C-reactive protein need priority treatment?