To preliminarily assess the acute effects of a single warm-water bath (WWB) on serum adipokine activity, we measured serum adiponectin, leptin and other metabolic profiles before, immediately after and 30 minutes after WWB in seven healthy male volunteers (mean age, 39.7 ± 6.0 years; mean body mass index, 21.6 ± 1.8 kg/m(2)). The subjects were immersed in tap water at 41°C for 10 minutes. Two weeks later, the same subjects underwent a single WWB with a bath additive that included inorganic salts and carbon dioxide (WWB with ISCO(2)) by the same protocol as for the first WWB. Leptin levels significantly increased immediately after WWB with tap water and ISCO(2) (both P < 0.05), and remained significantly higher than those at baseline even 30 minutes after WWB with tap water (P < 0.05). Adiponectin levels showed a slight, but not significant, increase both immediately after and 30 minutes after WWB with tap water or ISCO(2). Some parameters, such as serum total cholesterol, red blood cell count, hemoglobin and hematocrit significantly increased immediately after WWB with tap water or ISCO(2) (all P < 0.05), but they all returned to the baseline levels 30 minutes after bathing under both conditions. The sublingual temperature rose significantly after 10 minutes of WWB with tap water (0.96 ± 0.16°C relative to baseline, P < 0.01) and after the same duration of WWB with ISCO(2) (1.24 ± 0.34°C relative to baseline, P < 0.01). These findings suggest that a single WWB at 41°C for 10 minutes may modulate leptin and adiponectin profiles in healthy men.