The aim of this prospective case control study is to determine CD4(+), CD25(+), and FoxP3(+) T regulatory cells (Tregs) and T helper cells (Ths) in obese, asthmatic, asthmatic obese, and healthy children. Obese (n = 40), asthmatic (n = 40), asthmatic obese (n = 40), and healthy children (n = 40) were included in this study. Blood samples collected from children were marked with CD4, CD25, ve Foxp3 in order to detect Tregs and Ths by flow cytometric method. Statistical analyses were performed. p ≤ 0.05 was chosen as meaningful threshold. Tregs exhibiting anti-inflammatory nature were significantly lower in obese (0.16 %; p ≤ 0.001), asthmatic (0.25 %; p ≤ 0.01), and asthmatic obese (0.29 %; p ≤ 0.05) groups than control group (0.38 %). Ths were counted higher in asthma group than control (p ≤ 0.01) and obese (p ≤ 0.001) groups. T cell immunity plays important roles in chronic inflammatory diseases such as obesity and asthma pathogeneses. Decreased numbers of Tregs found in obese, asthmatic, and asthmatic obese children might represent a challenge of these cells.