Assessment of asthma with a control test is suggested as a relevant approach for recent years. Ideally, an asthma control test should apply not only to clinical manifestations but also to laboratory markers of inflammation as well. Until now, this could not be performed because of the lack of a confirmed marker which indicates inflammation. A fibrotic mediator TGF-beta 1 has been reported as a key mediator of remodeling in asthma. The aim of this study is to evaluate plasma TGF-beta 1 level in stable asthmatic sufferers and to investigate its correlation with the asthma control test. Stable asthmatic sufferers and healthy controls were recruited for this study. After obtaining demographic information, skin prick and asthma control tests were performed. Blood samples were collected for plasma TGF-beta 1 level. Any contributing factors that may affect plasma TGF-beta 1 level were excluded from both groups. Thirty-five atopic, 35 nonatopic asthmatic sufferers and 15 healthy control subjects were included for this study. The mean age was 38 +/- 10 (years) and 61% were female. When the asthmatic group compared with the control group, plasma TGF-beta 1 level was significantly higher in the asthmatic group (41.7 +/- 12.6 ng/mL versus 27.6 +/- 13 ng/mL) (p < 0.05) whereas it was similar among the atopic and nonatopic groups (41.8 +/- 14.2 ng/mL versus 41.6 +/- 11 ng/mL) (p > 0.05). Spearman Correlation Analysis results pointed positive correlation between uncontrolled asthma and plasma TGF-beta 1 level. This study shows that plasma TGF-beta 1 level may be a systemic marker of asthma control.